Click here for a nice big photo of the remote...
[Link: avsforum.com]As for the INPUT button, my guess is that that's the one labelled "TV/VCR". I don't know anything about WebTV, but if you can do what you describe using your WebTV remote, you should be able to teach the Philips remote to do it also, as it is a learning remote.
Rob
http://www.hifi-remote.com