If you're using a wired connection, you should be able to put youre ps3 online through a shared connection through your pc.
If you run a network cable,(not sure if one is supplied with the ps3, i should imagine it is) from your ps3 into your ethernet port on your pc (
http://socalfreenet.org/node/274), then connect to your internet from the pc,and go to your network connections,(Start>settings>network connections)(or from control panel).
Next, right click the active internet connection, choose properties, then click the advanced tab, and tick the box that says " Allow other network users to connect through this computer's internet connection", then click ok.
Now when your internet connection is active on your pc, your ps3 should be able to share that connection to go online.
Hope this helps, just give a shout if you need anymore info.