The SM2 setting has Mecha in it, you can find the rules in SM2 Armored Assault [AA].
I was in the process of creating a setting that combined the rules from BattleTec and SM:P but out group decided to go in a different direction. IMO combining the two would not be that hard as the CBT:RPG is almost a D10 based game, skills, backgrounds, life paths etc; should be easy to map to SM. The biggest problem I saw was that in CBT the mass of Mechs and starships is a lot less than in SM. One way to deal with that was to cut the mass of components and just say that it was do to new tech. This method was also shown in the AA vehicle book for a Mech that was described as in the employ of Imperial Special Ops.
Hope that helps.
MDC