The VG224 doesn't have to be connected to your network in order to use TFTP. If you connect the VG224 to your PC with a cross connect cable, you can install a TFTP server on your PC and then simply initiate the TFTP transfer from your PC. I would suggest that over XMODEM. XMODEM is a slow process compared to TFTP. I haven't used it in a while, but basically, you initiate the connection over the serial port, start the xmodem recieve process on the switch, then start the xmodem send process from your terminal program.

You have to connect the switch to your PC with a serial cable for XMODEM, so why not connect with a cross connect cable and use TFTP?

Just remember to assign both the switch and PC an IP address in the same network (ie. same subnet mask). You don't even have to change your PC's IP address (it will have to be manually set if you use DHCP though)