This is for anyone with an ANSI keyboard, us layout who just wants Colemak Dhm.  In a terminal:

git clone https://github.com/DreymaR/BigBagKbdTrixXKB.git
cd BigBagKbdTrixXKB.git

sudo bash install-dreymar-xmod.sh
sudo bash setxkb.sh -a "4c us us"

this should add an entry to your .bashrc file tmat looks like this:
setxkbmap -model 'pc104' \
  -layout 'us(cmk_ed_us)' \
  -option 'misc:extend,lv5:caps_switch_lock,grp:shifts_toggle,compose:menu,misc:cmk_curl_dh'

if you use a different shell like zsh, copy the above line to the appropriate init script.

If you dont like entering sudo all the time, you can do this, which will make your system slightly more insecure
sudo bash
chmod u+s /usr/bin/setxkbmap
chmod u+x /usr/bin/setxkbmap
exit