After much effort to find the correct components I was finally successful in setting my ICOM 710RT to allow programming of user memory channels (what a lame idea to disable in the first place). Hopefully my experience will save others some time and trouble.
Here is what you need:
EX-2144 Software (available from users on this forum or contact me). Note: this is the ONLY piece of software that will allow you to change this operating parameter on the ICOM 710-RT (no need to waste your time attempting to do this with other software). Note: you may find this software listed on bit-torrent and similar feeds -- these are, as suspected by another forum member
OPC-552 programming cable (RS-232 to mono pin...note: a USB cable or USB-RS232 emulation will NOT work). I purchased this via eBay.
Computer: This is hardest item to find. Must be a machine with a physical RS-232 port (not many around anymore, but some commercial
units still have them for control purposes). As noted, USB to RS232
emulation will not work. This machine must also be running native MS-DOS -- Windows emulated DOS (running "command" or "cmd") will not work. I used ISO disk burner software to create an MS-DOS 5.0 boot disk which also contained a copy of EX-2144.
Once all of these components are acquired the process of changing the configuration is quick and easy -- sure makes this rig much more convenient to use.
Be happy to provide more details to anyone who needs it.