if it was possible it would be ahistorical...cuz the roman, who are renown by their use of siege equipment didn't mastered the building of this devices in the begining of EB timframe..at first most of the siege weapons romans used, were confiscated from the cities and ppl's they conquered, and this was until the marian reforms..until then pretty much all the siege weapons the romans posseced were taken from the greek nations, who had tradition with this devices...yes, Rome at the begining stealed them, and kept them very well hidden as treasures, so they wouldn't be damaged, using them only when needed....it's stupid for rome the almighty potence, to not have them developed at first, but it was so...

but altough i love realism in my games, having to recruit, siege equipment is stupid...well to recruit siege engineers might be fun, if only they could use siege equipment, but that is not so in RTW...but not the equipment it self