I'm not sure why would you want to do that. In any case, you need to understand your requirements/use cases in depth and pros/cons (essentially relational database vs jcr features) of what you plan to do. There is no automated tool available to simply lift and land database into jcr.
You'd need to identify "detailed" requirements, create a design, data model, taxonomy, site structure and other aspects and follow the sample implementation as mentioned by Scott and create a full-fledged app for same.
Reference link -
DavidsModel - Jackrabbit Wiki