Update: A more updated beta version was just released (0.7-test2). Also, BitPim appears to support the Sanyo 5500/VM4500 if you set the program to the Sanyo 5300. Other models have not been tested.
The Bitpim project has released a new beta version that supports the Sanyo 4900, 5300 and 8100. Bitpim lets you browse and upload files directly to the phone over a USB cable. Supports Windows, Linux, and Mac OS X.