Hi and welcome!

Indeed, variants aren't completely supported. I've done quite a bit on the Linux side, but I did it my way. ;-) You will of course understand that neither Shai nor I can work full time to support locales, so I guess the real problem is the lack of a supporting community with clear goals; we haven't been able to agree on any standards for locales or anything like that... yet.

I'd say that PKL is your friend. With it you can not only get the remappings you want and bring them with you on a USB drive that you can use without install privileges, but you can get awesome tools like Extend in the bargain.

One slight hassle is that some security-related dialogues on Win7+ won't allow remapping so you'll have to type Ye Olde QWERTIE there. I've chosen not to physically remap my keys.

You describe the layout you chose as "completely mashing your keyboard"; that's not entirely specific but I'll assume you've gotten an Angle mod (for ZXVCB) and the "US/Universal" symbols? Did you get Wide with that, too (right-hand keys shifted one key to the right)?

If you're happy enough with the symbol mappings you used to have, you'll want what in the Linux files call a "Keep Local Symbols" variant. For PKL, that's really as simple as editing the layout.ini file you've chosen (its path is seen in pkl.ini) and commenting out or deleting the symbol key lines. If on the other hand you want to change anything from your system mappings you'll have to learn to edit key mappings.

The Angle mod, similarly, can be fixed by looking at the ZXCVB_ key lines in layout.ini. The only hassle is if you do want to use Extend, because then you'll have to make sure you're using a non-AngleWide pkl.ini; there are two in the PKL root directory to choose from and rename to pkl.ini.

A simpler PKL approach would be to use a VirtualKey layout, with which you won't get any of the Colemak[editionDreymaR] AltGr mappings but only what your system layout specifies. There's a plethora of these to choose from; you'll likely want VK_colemak_ISO. Using that, you should be nearly all set apart from your special requirements.

The Tarmak layouts are all VK_ layouts so they shouldn't mess with your symbols. Unless you use TarmakCurl you won't have any trouble with the Angle mod I think.

Caps-as-Control is doable with PKL (although I haven't made the lines for it; hope you figure it out from the examples in the layout.ini file), as is the " position. If using a VK_ layout, you'll want to change the lines for the apostrophe (and maybe the 2) key to a standard remapping line as seen in the fully-mapped layouts. Poke around and let me know if you can figure it out.

In my sig topic for Linux/XKB you should find what you need (provided you want to use my UK 'KS' Colemak); you'll have to choose the Caps as a separate option (hooray for modularity) and edit in the " bit in the symbols/uk file; you could just add a remapping line in the 'cmk_ed_ks' section after the rest of the mappings.

What you have there is quite a unique setup. By UK (ISO) variant, I assume that means you want backslash to be left of Z, but you still want to swap quote with @.  Probably the easiest would be to take an existing UK configuration and make your custom adjustments.

PKL is a good for this as already mentioned, as is AutoHotKey.  When I learned, I went the tarmak route too, and as I was mainly using Windows at the time, I used AutoHotKey.  It's easy to set up and very flexible so I simply made my own mappings for each of the Tarmak steps.

At the risk of giving you too many things to think about all at once, since you have as ISO keyboard, you might want to instead consider the Angle Mod (moving ZXCVB leftward by one key), and even Mod DH (but then, I would say that!).  You would then be able to use standard US style mappings for quote etc, but still get maximum benefit from the ISO key.

Yeah, I think you used the wrong pkl.ini, the WideAngle one. Read in my sig topic about the Wide and Angle mods, and you'll see what I mean.

You want the other pkl.ini, nonWide.

PKL is really very brilliant once you get used to it! If you only need the bare-bones remappings though, sure, use AHK. (You realize that PKL uses AHK though – hehe?)

Okay, sorry about the delay in getting back to you!

Yes, with Tarmak 0 and Tarmak 1 it seems I've chosen to implement the ZXCVB "Angle" mod (and it doesn't show up on the help images!) as defaults. It's really brilliant, as it lets you keep your left-hand wrist straight while typing. Shai himself recommends it. ;-) You can easily undo it, looking at the pertinent layout.ini file (for instance, vk_Tarmak0QWERTY_ISO is the directory of the Tarmak 0 step for ISO keyboards). Find the Angle part as seen below, and reverse the comments so the 'no wrist comfort' section is active, like this:

; ***** Traditional 'no wrist comfort' layout - if you have no VK_102 key (or WANT pain?!). *****
SC056 = OEM_102    VirtualKey    ; QWERTY <> (ISO only)
SC02c = Z    VirtualKey    ; QWERTY Z
SC02d = X    VirtualKey    ; QWERTY X
SC02e = C    VirtualKey    ; QWERTY C
SC02f = V    VirtualKey    ; QWERTY V
SC030 = B    VirtualKey    ; QWERTY B
; ***** 'Angle-ISO wrist comfort' mod, for a better wrist angle. *****
;SC056 = Z    VirtualKey    ; QWERTY <> (ISO only)
;SC02c = X    VirtualKey    ; QWERTY Z
;SC02d = C    VirtualKey    ; QWERTY X
;SC02e = V    VirtualKey    ; QWERTY C
;SC02f = B    VirtualKey    ; QWERTY V
;SC030 = OEM_102    VirtualKey    ; QWERTY B
; ***** End of key set affected by the 'angle wrist comfort' mod. *****

I'm thinking you've got an ANSI keyboard though? Have you got that key between Z and LShift, mark of the glorious ISO board? If not, then you need to use an ANSI layout to get the right symbol key mappings. Also, the Angle mod would have to be AngleZ or A-Frame if you want it (which I'm guessing you don't, since you think the ZXCV keys are in the "wrong" position with the Angle mod?).

ANSI and ISO keyboards have different scan codes for the OEM_ keys which include the ones you listed. A further possibility is that even though your keyboard may be ISO your underlying system layout may be ANSI (if, say, you use a US-based layout in Windows). If so, treat your keyboard as an ANSI one. The VK_102 key can still be mapped.

You don't really need to lose all the Extend mappings in the file. Just find the line with "extend_key = CapsLock" in each layout.ini you use and change it to "extend_key = none". My strong recommendation would of course be to learn Extend instead!

My first attempt would be to change the underlying system layout, as I think that may affect the key codes PKL gets. If there's a difference between using the standard US and the standard UK system layouts while activating PKL, you'll know more about what happened.

If not, maybe trying an ANSI PKL layout might help? The '\' or VK_102/OEM_102 extra key may still be mapped normally (SC056).