Can you tether via bluetooth?
I read on forum that one user managed to successfully tether his Omnia to an iPad via the WMWifiRouter, a program that turns the Omnia into a Wireless access point that the iPad can then connect to. I am nearly positive that this will not be able to be done over bluetooth, as the iOS and bluetooth are pretty restricted. Sorry I can't help with the BT issue, and I hope I have provided a decent alternative that you can work with. Cheers.