If your N900 is connected (has a publicly accessible IP address) and your computer/laptop too, then you can use SSH.

You say you don't have a router, but can we assume that you have a computer connected via ADSL/dial-up/cable/... ?

If so, try to start the SSH server on your N900 and connect from your PC. Report any errors you get (preferably in another thread, as your problem is 99.99999% not related to KP48 or any kernel for that matter).