Well thats the point of the polybian reforms... They make Taras and Rhegion capable of producing factional units. I think you also get some units in sicily and the Po valley although I can't remember off the top of my head.

As for the marian's you need to get to the third or possibly the fourth level of MIC before they will let you get anything other than those crappy citizen police thingy's outside of italian provinces. Try cheating the build of each level of the factional MIC's and see if anything comes available. Or, just check the recruitment viewer.