Your main problem might be the driver situation. If your IPhone doesn't have a standard driver for basic functions via (W)LAN, you have a problem.
I tested printing via Bluetooth (Epson PX701W with a generic USB BT adapter). If your printer does have an USB host port and supports an optional BT USB adapter, try it.
(Mini-) USB BT adapter's aren't that expensive these days.
//HSishi