How to make general units normal recruitable units?

[Rahl]

I'd assume generals units work off the same mechanism as mercenary units. The Libian General and Numidian Nobles for example.

Yep. There are models used more then 2 times for some factions, like the neitos or the germanic elites. Theoretical it should be possible to use a model 4 times on a battlefield, normal, merc, general and merc general.