Within Europe this is definitely possible, even outside the EU. Moreover, Cartier proposed ordering from overseas. This was for a more expensive item, though. They need to deal with customs and the like which obviously adds some cost to them.
I would imagine, it wouldn't be an issue to do this within Europe. I'm in the US and the item I wanted Cartier to search for in another market cost $12,500 back in 2008. However, they told me they could not do it. Perhaps they have relaxed that policy in more recent years and now they will search in other markets.