- Prolemak is Farkas Máté's own layout. You can see that it's very inspired by Colemak, but he chose to move around some keys. As the moved keys include rarely used ones that I think should've been left alone and shortcut keys such as B and W, I don't quite agree his layout but maybe it's good for typing Hungarian? No arguing with the fact that he likes it at least!  ;)

- Colemak and colemak-inspired layouts is one of the many layout packages you can download for PKL. You can also get layouts that remap only part of your standard keyboard, different variants of Dvorak and others, and layouts for typing classical Hebrew or Greek, diacritics and all! PKL is so much larger now than just a Colemak mapping. You can also download a separate standalone Colemak, which runs Colemak but none of the many other layouts - good if you want something simple and compact. Under Standalone layouts there's Colemak, Prolemak and that oddball EntiKey which was made by a German guy for typing one-handed (or two-handed if you wish). Haven't looked into that one.

- To use the Extend key in a layout that has this functionality (such as Prolemak), you hold down the designated key (Prolemak uses CapsLock) and hit another (or several) to produce a remapped keypress whereas the original function of the 'extend' key is only realized if it is released without pressing another key with it. The results are mapped in the pkl.ini file I think, so there's one Extend mode in PKL common for the layouts and the layout itself only specifies an Extend key. This is very similar to what I'm after, but only has one mode where I'm after several. In fact, if you try the Prolemak with the help image on and press CapsLock (provided you still have one, hehe!) you'll see that the nav keys use the same layout that I'm after! UNEI for the arrow keys, JH for PgUp/PgDn and ;O for Ins/Del (I'm still undecided on whether to switch JH and ;O but the idea is the same). The cool thing is that you're sending "real" blind keystrokes and not just character codes with it, so that, e.g., holding down shift/capslock/ctrl/i in Prolemak will give you a shift-ctrl-arrow which selects one word forwards!

Once again, I start looking into something cool and Farkas has already done it very well.

If you want the Extend/Transpose functionality in your layout in PKL, you can add a line in the layout.ini under the [global] section, like for instance the one from Prolemak:
[global]
extend_key = CapsLock

Keep in mind that if you use a commonly used key for this, the 'key-on-up' way of working may get annoying as will the accidentally transposed keys if you type fast. Therefore a rarely used key (such as CapsLock, the left Win key(?), or a rarely used letter such as Q or Z) is preferrable to anything you use much.

Where do you put in that code to remap your keyboard? Does it work on a Mac?

DreymaR: Is it better to use the official installed version? If so do you know how I can remap |\ and /? to be Alt Gr?

Using PKL is too slow to be of use. It's fine for typing single characters but using it for navigation ala Colemak.vim is not viable.

Is their a speed issue with your approach tomlu? I was wondering whether altering these lines from Colemak.klc might do it...?

2b    OEM_5        0    005c    007c    -1    002a@    007e        // REVERSE SOLIDUS, VERTICAL LINE, <none>, SPECIAL, TILDE
35    OEM_2        0    002f    003f    -1    00bf    007e        // SOLIDUS, QUESTION MARK, <none>, INVERTED QUESTION MARK, TILDE

Could it be as simple as changing those to be Alt Gr and then using continue using PKL.

Not sure why you have these speed issues. Do you have anything else that uses a keyboard hook? Multiple hooks can get sticky (such as my experimental script competing with a running PKL).

Speaking of what Farkas did to Caps Lock: My z key is remapped to AltGr. I experimented with triggering a z on release if no other key was pressed, similar to Farkas, but for alphabetic characters it turns out not to work too well.

one thing that bothers me about remapping altGr...
I just recently learned that the proper way to do chord (e.g. alt + key) is to use alternative hands, and never use the same hand (which I used to do! ctrl +c with two hands? blasphemy!). It looks like this is a big improvement. Ergonomically, chords are bad. I have pain in my hands and can tell already how much things have improved.

So consider this before remapping one side of modifier keys. I was doing this too...

Chords aren't bad by themselves I think, but awkward chords are very bad. I'm a bit surprised actually, at the fact that I don't feel my very frequent use of CapsLock for chording as awkward or painful - it does imply an increased use of the left pinky, and sometimes with other left-hand keys in chords!

For instance, to get an Esc keypress I'll press CapsLock plus Q. Pinky plus ring finger. Why isn't that difficult? I think it's because there's no stretch nor significant angling involved. I did feel the need to solve the problem of having to hit CapsLock together with Ctrl and/or Shift - on some keyboards it went well (I'd use the side/base of my pinky!) but not on others such as laptop boards. The solution is to use home row keys; again, no angling needed and little stretching.