Just completed my XM portable unit install. First, thanks to Mattbren for his help with the antenna routing, which was actually pretty easy. I used the Belkin TuneDoc cupholder mount, which is set up for the existing XM Roady2 mounting bracket, and also fits some other portable XM units (Roady, Roady2, MyFi, and Skyfi with an additional adapter plate. The mount is perfect for the Clubman, as the unit is solidly mounted, easy to reach, easy to read, and doesn't block any other switches or controls. It's under $20 at Amazon.com. I also got a short right-angle cable from riteav.com, an Amazon partner. It's a dual 3.5mm right-angle male plug stereo cable, 3' long, for 99 cents (!) plus $2 shipping. A surprisingly well made cable, it's superior to the flimsy cable I checked out at RadioShack for $6. A right-angle plug allows better routing of the cables, as the antenna and power cables are also right-angle.
I put the external antenna behind the existing antenna on the rear roof, (put a nice heavy coat of wax there first, as the antenna can lightly scratch the roof over time) then routed the wire down along the outside of the rear rubber gasket, coming into the rear of the car by crossing this gasket at the lower left of the left rear door. The antenna then runs along the underfloor cover support bracket, under the rear seat outer hinge (make sure you go under the hinge, not over, as this is a potential pinch-point for the thin antenna wire), along the outer edge of the rear bottom seat cushion, along the door sill trim along the floor, under the front seat just forward of the seat tracks, and then under the center console left side to the center console storage area and the TuneDoc unit. The antenna wire is very thin, and the various trims all have a little give, so it's pretty easy to work the wire under any trim just using your finger. Leave a little slack where the wire goes over the outer gasket, and where it goes under the rear seat hinge, just in case. It took about 15 minutes to get the wire routed, and about 10 minutes to connect the Belkin TuneDoc, the power cord, and the aux cable. I also used about a 10" length of split cable-wrap to keep the three cords neat, and just gathered any extra cord lengths in the little empty storage area at the bottom of the console, wrapped with twist-ties.
One final adjustment: The Clubman radio has an "aux volume" line-level equalization setting, which is set to "1" as a default. If you find that the XM unit has a lower volume than the CD or radio, follow the instructions for your radio to adjust the aux-vol setting. Mine is set to level "3" This setting is needed because many devices put out different strength line-level signals, and this adjustment equalizes the signal strength so the volume approximates the radio and CD volume. You only need to set this once.
Total install cost was under $25, and the XM signal quality is perfect! It's not a factory radio install, but it's also $975.00 cheaper than the Sirius factory package, and I can connect and disconnect the unit in about 30 seconds, and listen on my home stereo, as well.

 

Sound good. I've got my brand new Xpress RC waiting to be installed, but I won't be using the cup holder. Not sure where I'm going to stick it though.

 

Man that is a lot of work to get that antenna routed. Does anyone offer a windshield mounted antenna?

 

It's not that much work, it took longer to write-up than it did to install. XM antennas are designed to work on the roof of the car, not inside. Some XM users report acceptable reception inside a car in various locations, but the best signal is with a roof mount. There may also be easier ways to get the antenna routed to the roof. Anyone have any tips?

 

A photo of the installed Tunedoc: