I don't know but i hope yes. A cleric-type class would be awesome, like a mage but with skills in maces, armor, and new healing magics and very few offensive ones, like in the eye of the beholder. Focused on willpower and endurence, so he is less than a warrior and a mage in combat. that would be balanced. Some spells could be heal, animate dead, cure poison, cure illness, cure starvation...

Healing and curing starvation spells would make this game even more epic.

The classes are hardcoded into the game, so at this point, it's not possible. However, authors have embraced the creative gene of the community, so it's likely that we will either get this for Grimrock, or for Grimrock2 (their new project already in production).

I saw something on the Wiki for coding custom healing spells into a map; but I haven't seen any maps use them.