Please double check in the manual, but I think you can do morphing with a momentary footswitch by plugging it directly into the Profiler. That will be cheaper than a Boss EQ (although Boss/Roland make good momentary switches) and the switch will not require power like the Boss EQ. Depending on price (if that is even a factor), you may find an expression pedal that is of comparable price to a footswitch and an expression pedal would allow you to have more control over the volume change as opposed to just a binary off/on.
If you simply want an increase in volume, you will want the increase to occur post-stack / after the amp. You could morph the amp volume or use the volume pedal settings in the Rig section; set the location to Post Stack. You could put a clean boost(Pure Boost) after the stack and either switch if on/off, or morph it between two values you set up.
Once you start doing this, even with one switch or expression pedal, you may find that there are many other parameters you want to morph.