i tried to make vim switch to a copied lisp syntax when it boots up an arc file but i wasn't able to get even that working
as far as details for the syntax, i would say don't give the [... _ ...] notation any special color or anything
once you have something, anything really, i think it would be fine if you uploaded it to the anarki arc git wiki
http://git.nex-3.com/arc-wiki.git into the 'extras' folder