Is this possible? I heard it's based on regex so would a wildcard "*" work for all?

example:

It is not a good idea to introduce yourself as uTorrent because real uTorrent clients will know you are faking, uTorrent puts "FAKE" next to such peer. Of course trackers won't know that, so it should be OK to announce as uTorrent, however it is safer to be consistent and use the same client name and version for both tracker announcement and peer handshake.

About your question, I never tried this, I guess http at the top should work.