It is not usually possible to transfer directly into the multivalued database using ftp. However it is usually possible to transfer the files into a directory on the multivalue databases host operating system (NT , unix etc.,) and then simply copy them into a multivalued database file.
If your system has the ability to make a host system directory visable as though it were a normal MVdatabase file then this may be the best way to transfer the source code from your PC to the MV system.