I have a New Jetta and just moved my XM-SkyFi from my pervious car. After several hours of exploring the best option and mocking up several docking ports (for lack of a better word) I feel like I found a good way to install.
Parts:
Skyfi Cradle
Magnetic roof-mount antenna
Wireless FM Modulator
Clear Shipping Tape
Some type of Black foar or rubber
Double sided Tape
The final mounting location was forward of the gear shifter and Aft of the ESC switch.
I mounted the antenna center above the windshield and ran the cable in the Gap. About 24” down on the right hand column there is a gap the ties in to the front quarter panel and ran the cable in there to inside door frame. Ran cable under weather stripping and worked it around the side where you left foot would be then up on over brake & (gas) pedal. On the right side of the center console, forward of console handhold where it mates to the dash there is another gap. I ran the cable there in to the area forward of the shifter where the storage area is or where the ashtray goes. I plugged in the FM Modulator in the power outlet and put the wire in there with excess cable. Plugged all three wires in to in to the cradle. Attached about an inch of foam rubber to bottom of cradle and but XM-receiver in cradle. Place cradle behind ESC switch and angled forward until it lodge in place. Had to play around with the foam until there was enough to hold tightly in place. Looks good, wires are behind receiver. I used the shipping tape to secure the cable in the doorframe.
I programmed the FM Modulator frequencies in to FM-2 and have the Modulator frequencies switches facing forward so I can adjust frequencies while traveling. Also the Modulator does not really fit the other way.
I will do a few cosmetic changes but this should give you an easy, good-looking, functional install.
Let me know if you have any questions.
Doc