i did it in april or may from tidy cat as well.
i have 3 cats, 2 boxes, so i left one with the regular litter and started out with about 25:75 (lower amount of wood pellets) with a little slightly soiled litter on top of it. then every time i removed any waste, i added pine pellets until that's all it was. the cats had no problem with it so i started on the second one and it all went smoothly. it took maybe 10 days or so.
like 3gatos said, you don't need a special box. if you reverse scoop every few days, you won't get tracking. if you don't do that, yes, it will get quite messy with sawdust tracked everywhere.
i have not done this because i don't have a drill, but if you have about 1" to 2" clearance on the boxes stacked together (as in nesting) then you mark carefully placed holes (measure the pellets so the whole things don't fall through) and then you'll just lift off the top one and empty the bottom. you might want to get another same size box to rest the top one in while you do this, i don't know how fast you are.
you'll still have to remove feces as soon as you are able, but you can flush them which makes it easier.
i love it. no pee smell, and my cats seem to like it quite a bit too. that's kind of like liking toilet paper but you know what i mean.