Hum,
Yeah, the subst command can be used.
But the real problem is probably the software that JaXanim is using.
The music/recording program should remember where the file should be saved to (you can look in the programs registry to see the save directory path etc).
My documents are always loaded from my document folder in my D drive. My pirated music from a music folder on the D drive etc...If i load from anywhere else the program will then remember that new path.