I found this interesting coverage map:
http://www.ses-sirius.com/services/coverage-areas/
I also found this company:
http://www.1worldspace.com/#
I took my XM INNO to Canada and was told it would not work. It worked fine. What they meant was that "legally" I had to use the Canadian service to listen in Canada because of licensing issues. I listened to the US feed. I needed a good southern pointing position for the weak INNO antenna, but no problem, even out at sea on the cruise ship.
If the Sirius satellite is in range, you MAY be able to hook up. I did not research the XM system.
If it is like Canada, what they mean is that you can not take a US radio into Canada and get the Canadian service. The US service comes in loud and clear.
I read about some Canadians that bought US XM service but they were canceled as they could not provide a good US address for communication. I can not find that old info. Worked fine as long as XM thought they were in US.
So if you have a small unit like the INNO, take it with you, it just might work, but it may not. You might want to pack an external antenna for better reception.
Added info: In my research I found that the Sirius satellite are not geosynchronous and in fact orbit over Europe and swap off as they go over the US. What I mean from the above is that if they are continuously broadcasting and are not turned off over Europe and have a continuous uplink they may work. You almost certainly will not be able to use the European systems that share the satellite without a subscription.