Actually, I'm working with a Linux box as Internet Gateway, using also an asymetrical one-way satellite service. But, in my case, it is NOT Isat Platform, but Nebulink. I'm working with the same type of pci card that you, a B2C2 Sky2PC card, with the drivers for linux. It works OK. But, I'm pretty sure there is a SatDirect (or Tqrecv) client specially for linux, so, you don't have to emulate it via wine. I don't know where to get it, but I'm sure it exists.
In fact, I'm going to work with Linux and IsatPlatform in the next days, so, I hope we can keep in conversation to interchange ideas.
Let me kow if you find that client for linux, please.