Question though: Do slug men breed? Or do i have to just capture a whole ton?
They probably will. Their young may die horribly for various reasons, though. In .16 I modded gnomes to be tameable, but their offspring seemed to have the need-to-be-carried-around infant phase, unlike tigerfolks. Tamed gnomes didn't care for their offspring, so I had gnome babies crawling around very slowly and dying of thirst and starvation before they could get to the wells/food stockpiles. Chaining them next to water and food didn't seem to help; perhaps they needed booze instead of water.
Same here. Putting them in cages with a dedicated animal trainer keeps them alive longer, it seems. I've never had them grow to childhood, though. I've even set their baby time to 0 in the raws, and they still make babies instead of children.
I'm guessing it has something to do with the game mechanics. Baby gnomes chained up with a well one square next to them and food in all other adjacent squares will die, no exceptions (.16). I'd wager it's because there's a difference between the critters having free-roaming cubs (a la tigermen) and infants (gnomes, etc). Dwarven babies don't seem to eat; they get packed around by the mom--other intelligent races don't carry their kids around. Tweaking the maturation times wouldn't help because there'd still be that infant phase... Mod your animalfolk race to have free-roaming cub offspring and not dependant infants, and it'd probably work. The way things seem to be set up now, gnomes and the like are supposed to have the dependant infant phase, but when they're tamed, they don't care for their young and your baby gnomes/slugmen/whatever will just crawl helplessly around the fort until they croak, much like orphaned dwarven babies.
Maybe splicing raws from the tigermen into the race you want domesticated would help.