He's right. You can't do a native SyncML sync with the BlackBerry.
The Sync4J project has a BlackBerry j2me binary that may or may not be currently in a working state.
I use Mobical with a Sony Ericsson P910 at the moment, and a ton of other SyncML devices - its a real shame that the BlackBerry doesn't natively support it, but thems the breaks.
You could check around to see if there are any other options; the sync4j binary was the only one I've ever played with.