Evap of xylene is producing crystals, but the whole damn mess is still sticky almost a full week later... is there a way to evap off the xyelene faster and more completey? Can i put it in the oven on low or will that just bake the xylene in?

It's just a very thin layer at the bottom of the dish over the crystals.

... or do i need to scrape up, mix with citric acid/water and then pull and evap the water?

Why are you evapping xylene? You want a salt of the mescaline, not the freebase, right?

Typically this is done by mixing acid and water, and using this to pull the alks out of the xylene. If you've let it dry, some of the mescaline has probably converted the mescaline carbonate, so I'd dissolve it in water, base it, extract back into xylene, then salt it out by whatever method you prefer.

If you have fumaric acid, you could always try to precipitate it from xylene as the fumarate salt using FASA