I have an XM Roady II in my 2002 Tahoe. I run it into the tape player.
it works well, just have to deal with the wires hanging down.
you might check out www.blitzsafe.com
they make all kinds of interfaces to factory units. I am waiting on the interface to Alpine's aftermarket head units for my Jeep.
HTH
Jim
2009 Chevy Traverse
2004 Chevy Avalanche Z71- K&N drop in filter, Magnaflow exhaust, MSD ignition cables, B&M aux. TOC
2001 Jeep Wrangler Sahara- 4.5" lift, 33" BFGs, K&N FIPK FOR SALE!!!!!
2003 Chevy Corvette, 50th Anniv. Ed.