Looking at the schematic, I agree with Nomad100hd. A midi switcher for your amp, a loop switcher for the FX loop and a controller pedal to tie it all together would let you get what you want. Here's an example. You could have the midi controller set up so that with a single button press, The switcher changes your Nomad to channel 1 and turns on the reverb, while the looop switcher turns on a flanger and delay in the FX loop, to create a huge, ethereal sound. Then with another button press, the loop switcher shut off all of the effects in the FX loop, while the switcher changes the Nomad to channel 3, turns off the reverb and engages the solo boost for a dry, but searing lead that cuts right through mix. Another button press makes the switcher put the Nomad into channel 2, which you have set at the edge of breakup, and turns off the solo boost, so you can sit back in the mix doing some simple rhythm chord work.
The equipment needed to do all this will cost money. However, it would by money well spent, IMO. The MIDI set up will be more flexible, come with a warranty, and there will be plenty of people who will be able to help you set it up to get exactly what you want. Performing surgery on your Nomad's FX loop and switching system will not be as flexible, runs the risk of damaging or destroying the amp, and it'll probably be harder to get advice from others on how to get your non-stock amp to get to do what you want it to.
Check out the GCX Audio Switcher and the Ground Control Pro by VoodooLabs. That's the sort of equipment that would be ideal for this.
