You can configure StudioOne to record from the AxeFXII and use the audio interface to monitor; I do it and it works great. There are some differences in our systems, but I'll try to walk you through it as best I can.
What you need to do first off is create an aggregate device with your audio interface and the AxeFXII. That's about as far as I can take you in Mac land because I have on idea how to do it, but I am doing a similar thing with ASIO4All in Win7. This basically allows you to record with one audio device and then route the audio output to another one. Aggregate device, look it up and you will have the big stunbling block out of the way.
After that is done we have to figure out how exactly you plan on recording. I use analog for wet and the USB for dry. I know that I could use the USB for both, but I've done A/B comparisons and all kinds of other crap and to be perfecly honest the analog output sounds great, my audio interface keeps it nice and clean and more importantly it's very low latency and I don't have to worry about jitter, drops or pops or whatever that 'can' happen with digital. It just works for me. If you do go with analog make sure that you use balanced audio if you can because it is a lot cleaner. If you are just using USB then just hook the cable up.
Open up StudioOne (S1 from this point forward). Create a new song at 48kHz, 24-bit.
Next thing is to configure your audio I/O from within S1. This is where the aggregate stuff becomes important. Click on StudioOne -> Options and then the Audio tab. You should see one 'device' and all of your inputs from the audio interface and then the AxeFXII (it will probably be stereo). Go ahead and add 2 more stereo channels from the bottom. We're going to select 1/2 from the audio interface for the first one, AxeFXII 1/2 for the second one and AxeFXII for the third one. I would go ahead and double click on the names of each and give it a good name so you know what they are later. Open up the Output tab and it should already be on your audio interface left and right already.
Now this is where you are going to have to know your audio interface a bit more indepth because the output channels you select here (usually 1/2) will have to be what you are using to monitor with from within you mixer app.
OK, now right click in the track area and add a stereo track. You should see the name for the default audio device; click on that and select the AxeFXII 1/2 or 3/4 (I can't remember which one is wet and which is dry). Hit the record enable button and you should here something at this point from your audio interface.
Once you get to this point let me know and we'll see how things are going. There are some other things that we can do in there depending on how well it works at this point. We aren't set up for zero latency monitoring yet so if there is some delay don't freak out. I just want to make sure that you get to the point where you can record and monitor before we get deeper.