I think the Reinforcement Character rules are pretty good and can be expanded to included more then just an RC. Only issue is coming up with the IFL minimum and the IFL cost.

What would be the cost of say getting a Imperial Navy ship as "reinforcement"?

What about getting a company of Imperial Guard?

~ alemander

Considering a single Grey Knight is IM65 and IC16, and assuming that they each have half the destructive power of a full IG regiment (based on fluff and tabletop interpretations of power level), then bringing in a full IG regiment should require twice that. Unfortunately, IM130 is pretty much impossible so why not just leave that at 65 and increase the cost to 25 (so as to avoid eliminating all of the characters influence in one go). Therefore, IG Reinforcement IM = 65 and IC = 25.

A ship could be very variable, depending on which type of ship you are looking for. A good rule of thumb would be to require the players to pool their influence to acheive the previously mentioned IM130 and to divide the IC32 equally amongst the players.