Yes this is possible to tether you're WiFi iPad to you're Bold, however it uses a program called iBlueRiver and uses modem mode on the BB and is deathly slow.
I have it running on mine, but dont end up using it due to the speed.
This is also currently the only possible solution out there, I mean it WORKS, but not worth it for constant surfing etc, good if your caught in a pinch however!