Need help with aux input/aftermarket Sirius hookup.

[GWZall]

I bought an aftermarket Siruis unit for an M35 and want to hard-wire the connection. I have seen products that provide aux input by connecting with factory hookup, but nothing that will fully integrate (not replace functionality). I don't need anything complex, like integration with the display panel, but need some way to link the Sirius unit to the factory stereo.

Any ideas?

Thanks for any help!

Greg