ReDirect /
http://www.newsite.com/
:-)
Should work just fine.
If you want to omit the paths after the domain and make all the traffic go to the main site on the new domain, do it like this:
ReDirect /
http://www.newdomain.com/?
:-)
Anything after the ? will be disposed of because they will be treated as query strings. :-)
SplitInfinity should be hosting you if your host cant do that. :-)