I've just had a quick play with serial to usb converters, they happily remap to whatever free com port you want so as soon as the level shifter comes through I'll marry them up and see if it works. (Chronys.exe detects it ok so fingers crossed)

(I have literally dozens of the serial-to-usb interface cables, so if this works I'll happily post them out to anyone who wants one for P&P charges)