Our MC club did a poker run several years ago.
1. Set up/plan the route - have an alternate in the event of construction
2. Secure donations for prizes
3. Get lots of help to man the various checkpoints
4. You may need liability insurance in case someone gets hurt
5. Print up liability waver forms
6. Hope for good weather or pick an alternate rain date
7. Set the rules and stick to them - ie: time first bike out, time last bike in, etc.
It's a lot of work but can be fun for the people riding.