Only the gateways that are listed are supported in Power Store. it is possible to hand code the functionality to process the transaction through other gateways, but that is not something that we can offer support through the forums for, if you would like assistance using another payment gateway, we could help hand code that in a premiere support appointment.
I'm not sure why IE would hang on processing the order, can you send a URL to your site so I can take a look to see if something jumps out at me.