used the tracker with Virtools and there there was a building
block where u can say tracker and localhost (or any other ip) to
use this trackerdata.
unfortunately vvvv doesnt provide a node like this up until now. we´d need to program one into vvvv, and the code on the VRPN page would be a great help in doing so. if you are able to touch money we can think about this. it can think of it being cheaper than buying an IsoTrak.
Apart from that there still might be the possibility of patching a driver: I spend some more twenty minutes trying to track down the data format how the devices communicate on a network level without using the provided VRPN DLLs. Unfortunately i did not find anything. Somebody needs to dig deeper here, or use something like EtherReal to observe the actual traffic on the net. It might be some really trivial format, it might be not. Depending on that it might or might not be feasible to create a patch which is able to speak to a VRPN server.
here is a part of the config file for vrpn.
sorry that doesnt help. check if polhemus provides a document of how to talk with the Tracker directly via RS232. The idea would be skipping VRPN here. The code within the IsoTrak node is not complicated at all, so this particular brand might be similarily simple to decode.