If you just need a one-time move, a file packing tool -- like PKZip/MVS or UnXMIT -- to bundle the source up. You can then transmit it using IND$FILE, ISPF File Transfer or FTP to your clearcase server and check it in.
If you need ongoing updates of your mainframe resources on a server based source control system, you might be better off setting up some shared DASD using samba, NFS or the like between your mainframe and your server.
Unless you plan on doing your development on PCs, I don't think Rational Developer for Z is going to be a good fix. It will do what you need, but the mainframe setup is kind of headache-y and the cost of the product is excessive if all you need is to move resources to/from your clearcase server.
IIRC, RDz costs about 6k per seat. You might spend a few days writing some procs to ftp to/from your clearcase server and check-in/check-out and save some heafty expense. Actually, IBM ought to already have those tools built already. Clearcase supports remote machines doing checkin/checkout, maybe all you need is USS and a TCP/IP connection.
