Like this ? Gateways
Inspired by this article ? PlayGM naver.com cafe (need to login)
This example helped me quite a lot ? Split Screen Concept by David
Download ? Portal Test Remake(1)(1).cap
ahaa... plz ignore strange words. It's my language; but I forgot to edit it.
<img src="http://desmond-secure.yfrog.com/secure_scaled/large/814/yhhi.png" border="0">
If link is broken, Download it from here.