According to the FAQ the reqs. are to:
-At least the year 172BC
-Have more than 6 Latifundia built in Italy
-Hold at least 45 settlements
-Fight more than 250 battles
-Have a character that is:
Sharp/Charismatic/Vigorous
Popularis
Consul or Ex-Consul
Has Influence > 2
Has Command > 2
OR
-Conquer 90 settlements.
Latifundia were the best level farming in Vanilla RTW IIRC but it seems to have changed in EB so could someone tell me what Latifundia in EB are?