The jSyncManager is a Open Source, Java implementation of a HotSync-compatible protocol stack, set of data abstraction objects, development tools, and applications allowing developers and end-users to synchronize Palm devices with any Java based system.
Jsyncmanager works perfect.
I used this tool to develop custom sync application for a PalmOS app written in SatelliteForms to automate field operations for a pest control company. It worked great, and I contributed back a library to handle SatellitForms data files. I know PalmOS is a legacy product, but if you need to work with it, this tool is tops.