swiftone, find out if they are using the "Unix System Services" (I think it has been renamed to something else lately). It's essentially AIX-on-bigiron, uses TCPIP and it even does Perl. (if you need to do something on their side, it will make it easier if you don't speak SPF, JCL)

Thing is, MVS does TCPIP, you should be able to just FTP to it and download, in fact I am supporting a training system right now that uses FTP to get an MVS dataset for loading into an Oracle system. I just looked at the script, it just uses system to pass an FTP script, no magic involved at all.

good luck!

Update here is a link to the IBM Redbook on TCPIP/MVS: IBM TCP/IP V3R1 for MVS Implementation Guide, GG24-3687-02