I personally think it is better to call, rather than send in materials. The naterials can be ignored (for a variety of reasons), but it is hard to ignore a telephone call.
Tell the recruiter what you want. It is not very picky at all. Again, the recruiter knows the managers, and just might say, "Well, there is only a full time position open, but I know Mary-Jo, the manager in Rehab might be able to split the position...let me ask her". On top of that, the recruiter is aware of things before they get posted on the web site, so might have more information for you.
Then, of the telephone, ask the recruiter hwo she would like you to proceed. This way, you have a person to send your materials "attention to", and you can refer to your phone conversation in the cover letter, making the letter a little easier to write, because you can say, "as we discussed, I am most interested in XYZ, but would also be enthusiastic about a different option"
Wow, this was a long post. I hope it is helpful, and not just mindless blathering.