I just took a look at how this feature is exposed. I really wants this feature. I hit the 2,100 parameters limit of SQL Server too many times in the past, always when I had to do some large IN queries. So, I was very happy to hear about that feature, but I didn't really take a look until now.
Unfortunately, the way they are implemented requires a hard reference to them. You have to create the type in the server, and then you have to reference it by name. Annoying, to say the least, and it looks like there isn't any generic solution that I can accept. This is bad because I can think of quite a few uses for this feature, from applying batches to complex queries, it can be very useful, but it is looked in its own safe, statically typed, world. Urgh!