Upgrading a MacBook running Leopard to Snow Leopard using a Restore disk from another computer.

Okay guys, I need to update a MacBook running Leopard to Snow Leopard using a restore disk that has Snow Leopard on it. Dont tell me it cant be done, because i have before. I dont remember how but i did. I can upgrade too because thier is an OSUpgrade.pkg in the Packages folder on the disk. IF we could figure this out, we all could save some money!

So far i am able to get into the packages folder, put i need to view the contents! Suggestions?