To summarize what others have said, this wireless sync is a BES feature and not available natively on BIS. Your only choices are:
Hosted BES
Google
The Google route may actually work for you. You need something like this:
https://tools.google.com/dlpage/gappssync
Folks are getting great results with this method.
If you prefer the hosted BES solution there are some good possibilities in the
Sponsors area. Exchange My Mail and Link2Exchange are both highly regarded.