There is a way, i asked the same question a while back when i tested P3D but i cannot share how i got them to install/work with P3D :(

I only installed them for testing reasons as part of my one month trial of P3D and at the moment i do not have P3D installed so my CS products are only installed in FSX. The 757 worked like a dream btw :)

P3D imo needs to mature a little more before i consider to move across to that platform and i hope in time CS will sort something out to allow us to use our CS aircraft in P3D :)