DoMePlease,
Why don't you keep a (clean!) hanky in your right trouser pocket (assuming you are right handed) in order that you can covertly wipe your palm immediately prior to walking through the interview door (withdraw your hand before entering the room). Then, before you've a chance to get sweaty again, the initial handshakes are over.
In all probability, handshakes are required at the end, so towards the conclusion of the interview rest your palm on your leg. As you get up, the movement will automatically wipe your palm dry - and will be disguised to the interviewers. Do not sit there wiping your hand on your trousers though, or obviously wipe your palm on the side of your leg before shaking - very off-putting.
This technique has got me through many a summer meeting!!