Phone as router while using computer's internet?

[stab244]

Okay so here's my situation. I know that the TP2 can be used as a Wi-Fi hotspot with the data connection from the mobile network provider. In my case, I have T-Mobile USA and on pre-paid (don't knock me for that...) and I can access T-Zones with that for free. However, I was wondering if I can do this crazy thing...

I know that if I connect to my PC and establish an ActiveSync connection between the two, the TP2 and the PC, I can use the PC's internet connection on my phone. I'm wondering if I can take it one step farther than that and make it so that while my phone is connected to my computer's internet, it is able to broadcast that internet connection through the Wi-Fi Router. I've tried looking through the settings for this and I can't seem to find it. Everything that is there involves me using the mobile network's internet as the data source for the Wi-Fi Router. Reason for me wanting to do this is because... Well... My DS can't connect to WPA2 connections and that is what my house is currently using. I want to use my phone as a secondary router that uses WEP security for the moments when I need to go on Wi-Fi with my DS. Any way to do this? Thanks to anyone who can help me!