'97 Ls400 Aux Input Options

[Rumplestiltskin]

Helping a friend install his XM receiver as neatly as possible and also trying to improve the sound quality. He has a '97 LS400 with the premium sound system (Pioneer?). He said he never uses the glovebox mounted changer, so I wanted to see if it was possible to use the signal line for it to attach the XM receiver.

I think he'll be happy enough with just having all the wiring cleaned up, which should be a snap. But he occasionally has interference using the FM modulator, so a direct connection using the XM players lineout would be ideal.

Any chance this is possible? I've found references to people have some luck, but most cases were with different models, and nothing really definitive.

Thanks!