do you mean electrically in series or parallel? or wort flow series/parallel?
in fact, now that I'm thinking about it, you want an element that you can go full throttle for steps, but manage the wattage for temp maintenance. how about this....
a 220V 5500W element will only operate at 1375W when at 110V, a 4500W 220V will be 1125W at 110V (a 220V element will operate at 1/4 the power when run at 110V). pick either one you want, but using one of those, you could have a system that can put 220V on it for manual step up, then switch over to 110V for PID controlled temp maintenance (you could use PID for both, but wiring might be a bit more complicated). that could be a fairly easy way to get both high and low power in a fairly compact setup.