You'll have to do a little bit of burping. Just drain it enough to empty the tank. Maybe a little extra so it's not stuck in the hoses. Then refill once the new tank is on and then check it at the crossover. It shouldn't be too bad as long as you don't completely empty the system.
That being said, I bought one of those vacuum set ups for checking for leaks and filling the system. Frickin awesome. Helped me find a couple leaks on my son's car in no time. Made refilling my car after draining it quick and painless.
There is a good way to do it that will save you so much headache. If you draw it down and replace it, you'll have to burp it. BUT- if you clamp off the hose just below the reservoir, you can siphon off the reservoir and replace it. No real need for burping then because you don't end up draining any of the engine.