There's another package called something like XTNDConnectServer. I downloaded a free trial version, in the hope of doing exactly that. It might be capable of doing it, but I'm not capable of setting it up to do so. I removed it from the PC and didnt' buy it.
I synch my iPaq to the PC with MS ActiveSynch, which loads diary and contacts into Outlook (which I don't use for anything else), and Excel and other useful files into a directory where I can work on them.
I use XTENDConnectPC to upload/download stuff to and from the Z600 via the IR port, including phonebook and diary.
I can also send files directly between the iPaq and the Z600 using Bluetooth.
Do you actually need XTNDConnect for the iPaq?