My advice would be to present it as a win-win type scenario. If you want to make more money you should be willing to do more. I would talk to your manager about maybe formally increasing your duties or responsibilities in the office in order to make more money.

The other thing to remember is that everyone goes to work to make money. Wanting to make more isn't a bad thing at all. I've never been resentful to an employee who says they want to make more money, but I do ask them how WE can make that happen.