Fire up Gnome Editor, open the Unit_Prod file it's column 11.

There are many labels, first the religion/culture specific (CATH, ORTH, MUS & PAG [You could probably add JEWISH to that aswell])

_REBELS()
_LOYALISTS()
_PEASANTS()
_BANDITS()
_ZEALOTS()
_HERETICS()

Then the less generic:

MONG_RAIDERS()
ENG_BANDITS()
CRUSADE()
JIHAD()

IIRC values between -15 and 15 should be inserted in brackets to increase/decrease occurance of appearance. If you don't want a unit to be available for a certain rebellion remove the identifier (for example you don't want Artillery in a rebellion remove CATH_REBEL(2)).