How do you connect to the Internet via a Nintendo DSi, with DGamer?

Hi, I would like to know how to connect a Nintendo DSi to the Internet. I know how to connect it with the System Settings, but I don't mean that. What I mean: In some games, you can connect to the Internet with DGamer. I know how to connect that to the router, but I can't enter my pword for the router, because in the connection settings you can only enter a WPA key. The Problem is, my router uses a WPA-PSK key. It is a Thomson router. Please help me as soon as possible.