For what its worth, I have actually found a workable solution to this
Get on the Bay of E and pick up an old Harmon Kardon Drive and play unit - they are getting a bit old now, but there are still a few new ones kicking around for about £40 or so. It has AUX in, and full iPod controls - works pretty well.
It has the option of a hard wired FM modulator, which whilst not great, is better than nothing, and will give you some decent tunes on your head unit if you tune the radio in to it. BOSE owners will be more than happy with the sound.
Now, this is where Modulators and the Omega do not usually work.
The FM aerial in the Omega is piss poor, and it struggles to give a strong enough signal to the poor quality tuner inside the original radio. Adding an extra few joints and a modulator in line with the aerial cable are usually enough to kill the radio signal strength completely, and most find that whilst the modulator plays the MP3 tunes, its at the expense of being able to listen to the radio ever again.
The solution is to fit an EXTERNAL FM AERIAL to the roof instead of the crappy thing stuck to the window. Even if you have an existing aerial on the roof, then you will need to replace it for this to work. Use either a BOSCH or HISRCHMANN fully amplified beesting aerial, and a tip here is that AUDI ones are cheaper than GM and have the same upright mounting angle - VW ones are more swept back and there is no problem using those if needed. If you use the telematics, then select the correct aftermarket aerial that has the dual/tri/GSM/GPS configuration for your needs. When new aerial is fitted - DO NOT USE ORIGINAL CABLES as these are poor also. Run a new aerial cable from the Aerial to the Modulator, along roof and down O/S A post to the Modulator in centre console, and to the back of the radio. The replacement aerial will require a 12V feed to its base, and there is no problem connecting this to the little spade connector that you unplugged from the old Vx one.
Just to add
We have tried other modulator kits with zero success, and tried existing cables with zero success
So far, the combination as suggested above has worked every single time without fail
Hope this helps