I use the excellent AutoPkgr, in conjunction with JSSImporter. It runs every night to download and create packages. I have it on my master distribution point. 

However, it currently (1.3.2) supports only SMB and AFP distribution points. 

If you need to setup a local repository, follow these steps. Make sure you change the index number if needed (here=0).

Here's how it looks after:

Please bump ER: python-jss: Add Local Repositories #463 if you feel this should be implemented.