Dremel rotary tool and diamond burrs, and many test fits until it worked , then a paint job.
(there was a url link here which no longer exists)
An alternative is to re-spool film onto a 620 spool.
One more thing, if you look in the feed side of the Tourist, at the bottom where the spool rides, you will see two rails that the center post is between. These must be ground down just enough to allow a 120 spool to be inserted. 120 and 620 film are exactly the same, the difference is the spool. The dimensions between flanges is the same, the difference is the flange thickness, making it appear that 120 is wider film. I have a Tourist II and an original Tourist that I may modify in the near future, if I do I will take photos of the procedure and post them. You must be careful not to grind the chrome tension finger that's in the back on the bottom, it will ruin the backing paper and film as it winds past it if it's sharp.