On UC500 the softkey transfer will act same as flash for these users, on a call transfer softkey places first call on hold, new dial tone, dial transfer too extension, transfer softkey to commit the transfer, before or after ringing party answers.
The flash softkey on UC500 is to flash the CO line, Centrex enabled, not to transfer calls within the UC500 system itself.
So same procedure, just tell them Transfer softkey is same as flash. You can't rename the softkey though...
Ron Lewis
Cisco