Yes you can. PocketMac allows you to select which items are to be sync'd via USB: eg calendar, contacts, notes and tasks. It also lets you choose whether you use Entourage, the native mac programs like iCal/AddressBook or another third party PIM called "Now Up to Date/Now Contacts" or something like that for desktop software.
I don't think you can use the Mac AddressBook/Calendar apps through the BES, however: there are two apps from
www.snerdware.com that claim to sync the mac calendar and addressbook through a BES, but I have not had much success with them.
Also check out :
www.epicad.com I am not sure if it allows you to access a Novell server or only an MES.