Ctrl + Up/Down to scroll through Terminal.app window

I just ran into what I think is the same problem when trying to use Ctrl-S under Vim in Terminal.app. I found a related tip indicating that by default, Terminal.app reserves Ctrl-S for old-fashioned XON/XOFF flow control. Adding this line to my .bash_profile -- or just entering it at the prompt -- freed up Ctrl-S and Ctrl-Q for use with Vim:

stty -ixon -ixoff

To use a mouse wheel or trackpad to scroll in Terminal.app you'll need to install MouseTerm. After installing MouseTerm you'll need to add set mouse=nicr to your .vimrc file:

echo "set mouse=nicr" >> ~/.vimrc

If you're still not able to scroll in elinks it's possible that it wasn't compiled with GPM (General Purpose Mouse) support. Since elinks isn't a native application to OS X you probably installed through MacPorts or Homebrew. I'd open the "formula" file for elinks /usr/local/Library/Formula/elinks.rb (by default for Homebrew) and verify that --without-gpm isn't anywhere to be found.

Though your question states you want to do this in Terminal.app I'd recommend taking a look at iTerm2 which supports this natively, and has quite a bit more to offer then the stock Terminal app.