I asked the same question privately on RFF some time ago, and bob338 kindly replied me:
"nearly impossible. getting a single roll out of a 400' roll without dumping the whole thing over is impossible in a bag. not to mention the dust and scratches you'll get, too. "
"i wish they did, but i've never found a bulk loader that will take 400'. if you're buying XX or something in 400' rolls, they are really easy to split into 200' rolls for these loaders. lay it on a table with 2 screws in in to keep the cores in place and keep rolling the new roll until it's about the same size as the other. you obviously need a darkroom to do it. if you try to split a 400' roll in a bag you will scratch the film and probably lose your mind! trust me, i've done it. splitting it into 100' rolls is just as easy but it takes more time. XX comes on a core with no sides, so when you open the can do not let it lean to either side or it will dump all over the floor and you'll never get it back without messing up some of it."
You can try to get an Alden model 72 bulk loader, which can take up to 200'. But it is very hard to find. Or you can try to split it into 100' rolls. The core coming with Legacy Pro bulk film is perfect for this purpose. I recently unrolled a 500' polypan f roll into three 100' Legacy Pro bulk film cores.