Hello,
Currently, the rules in Field Manual: Mercenaries (Revised) and the point-based system in Mercenaries Supplemental reflect the most current rules for creating mercenary commands. Because of the myriad possibilities available, there's not exactly a "start with X C-bills and buy stuff" process involved here. It isn't, after all, like banks exactly fork over millions of C-bills in loans to every disgruntled officer or noble who wants to form his own outfit. To reflect this uncertainty, both the FMMR and MS1 approaches use a point pool system that's affected first and foremost by the nature of the commanding officer, and then by other options he chooses when creating his command, such as how long he works on recruitment, how much prior combat experience he tries to pick up before his force is complete, and so forth. It's far less cut and dried as the version of merc force creation shown in Mercenaries Handbook: 3055, but ultimately more in tune with the feel of the universe at large. (We hope, anyway.)
Hopefully, that helps.
Thank you,
- Herbert Beas
BattleTech
Catalyst Game Labs