You could try to use the ln_Name field. I doubt that it is used by the IORequest.
However, what you try to do is more than suspect. Device I/O is a private issue, you should only use WaitIO to remove messages from the port. If you do it with GetMsg, some parts of the I/O protocol might not get done. The easiest is to use a different port for each IORequest.
Bye,
Thomas