I plan to do this shortly on my car and have done it numerous times in the past. If I recall correctly, there is a small clip that holds the odometer spool in place. Once the spool is removed, there is a paper retainer that holds metal tabs between each wheel in parallel with each other. Remove that and you can spin the wheels independently of each other until you get the desired mileage. Reassemble and you're done.
No exploding ink bags, no trigger springs, no mess, no fuss, no strain, no pain.
