Have a Nissan XM Radio Installation Question

[DConrad2007]

I have a 2004 Nissan Maxima SE without the Bose sound system, I just have the standard Nissan factory radio with the SAT button.I have been searching Ebay for factory XM tuners and every seller saids the tuner will only work with Bose or Clarion radios with cd/changer.Also I've been reading that the vehicle might not be wired for XM.Today I removed the cover that hides the rear spekers in the trunk to see If I have the N-Bus connector and found a 12-pin connector with blue tape around it to protect it hanging there.Isn't this all I need to connect the XM tuner to my factory radio with a XM antenna?I don't understand why you need the cd changer to make the factory radio function with a factory XM tuner.