I'm not doing too many monsters these days, mainly just portraits, both human and animal!

I'm glad that you are finding the tool useful! the shortcut for Select Layer Contents in ArtRage is Ctrl+Alt+A which in the autohotkey script world translates to :
^!a

this may look like gobbledegook but for autohotkey
^ is Ctrl
! is Alt
and a is a

Also + is Shift

So in the section towards the bottom of the script that is :

ArtWarp:
WinActivate, ahk_exe %ArtName%.exe
Send ^w
return

Replace the ^w (which is the key combination of Control + w) with
^!a

and for extra brownie points, to change the name of the button from Warp, modify the Warp text at the end of the following line :

Gui, Add, Button, x+5 w40 h30 gArtWarp, Warp

Good luck!!