Really wouldn't work too well as all the heavier components will be spun to the side of the can, similar to what a centrifuge would does.
Monty, you totally missed the concept here in this excellent tip.

Once the can is mounted in the chuck, you turn on the lathe, (medium or slow speed). Then grab the lathe somewhere along the lathe bed, and commence aggressively shaking the lathe for about 60 seconds. (Longer "Shake Time" required if the prospective paint sprayer is either a wimp, or has just bought his (or her) brand new lathe, and is a little tentative about giving it a good shake.