yeah I used a pillow case that I kind of modified... I cut the top ring off a bucket and threaded that into the 'lip' of the pillow case to hold it open. I also cut about half of the other end open, so I could get him nose into the pillow case while holding the end shut, then let him swim out in the new tank. Worked like a charm, the only problem was he got VERY upset when I first tried to get him to go in there. It never ceases to amaze me how strong and fast they can be in fight or flight mode!
The foreshortening effect of the glass makes him look a bit smaller than he actually is. I measured him a few months ago when I brought him home at 28".