Sbopkg to manage local handmade slackbuilds

I'm starting to configure a Slackware Current system maintained with following tools:

1. slackpkg, for official packages and some other from unoffical precompiled repos
2. sbopkg, thanks to Ponce SBo-git repo, for other software built by SBo slackbuilds
3. moreover I use to re-build few packages by hand, editing some slackbuild of Current official repo or from SBo, or again writing scripts by myself.

I'd like to manage the third group of packages with sbopkg. I read it is possible to maintain a "local" repo and use it with "sbpkg -V" option.

So my questions would be:

• how to set up that local repo? (have I to create some directory hierarchies under /var/lib/sbopkg ?)
• how should slackbuild scripts be written to works properly with sbopkg? (have I to follow the whole SBo guidelines? Or for a local repo, I could respect less rules? Which ones exactly? Which variables are really needed by sbopkg?
• which other files are requested in the "build dir" (I noticed README, slack-desc, ".info" and possible patches, which ones are really needed for a local repo?)

If you know any link to docs where the above questions are well explained, would be welcome.
Thanks in advance! :)