You can use Intellisync for the GroupWise end, however, some versions of ActiveSync will cause GroupWise to be duplicated into Outlook (whether you use Exchange or not) and then sync from there. Best bet is getting the newest version of Intellisync from Pumatech. It's got more features that the last version. I use an Ipaq 3870 and all is working quite well.
Check that the user has admin rights during the install or else none of it will work.