Mac OSX 10.9 ships with the Dvorak keyboard, the Dvorak – Qwerty ⌘ keyboard, and the Colemak keyboard, but there is no Colemak – Qwerty ⌘ keyboard.  Here it is:

Colemak – Qwerty ⌘.keylayout
Colemak – Qwerty ⌘.icns

You will have to unzip them and make sure their names are as above.

To install for your user account only, move both files into ~/Library/Keyboard Layouts/.  To install for all users on your mac, move both files into /Library/Keyboard Layouts/.

To view/use installed keyboards on your mac, go to System Preferences > Keyboard > Input Sources, then click the + symbol on the bottom left. Choose the Others category on the left sidebar to see any manually added keyboards.

 

I created this using the Ukelele application.  If you want to create your own custom keyboards, follow these directions:

On the Ukelele disk image, open the file /System Keyboards/Dvorak/DVORAK-QWERTYCMD.keylayout, which is already set up with the ⌘ key separated from the regular keys (this was a good choice for my goal).

Keep View > Sticky Modifiers checked, because it enables the ability to edit ⌘ and shift inputs when necessary.  Use Keyboard > Edit Key… to change key outputs to Colemak outputs.  Sometimes changing a key will also change that same letter elsewhere on the keyboard (often when ⌘ is selected).  When this occurs, use Keyboard > Unlink Key… to disconnect the offending key.  Repeat this process until all keys are changed.  Easier said than done.

To create an icon for your custom keyboard, follow these directions:

Use Icon Composer.app from the Apple Developer Website under Graphics Tools for Xcode – Late August 2014 (download the entire .dmg file).  That application allows you to bundle up images into a .icns file.  Do not use Preview to save .icns files, since it does not handle them properly.