I'm not sure if the iFile app is still available for iOS versions that old. You'd have to check Cydia -- 3.1.3 should have it. I don't recall having it on my former 2nd gen touch with 3.1.3 on it -- but I might have.

The default way I use to access the root directory of my iPad (and all my previous iPod touches) was to use openSSH and use Fugu to SSH into it. iFile does have a webserver feature.