There are 2 main external JET resources.
There is a mailing list run by JET users at JET Yahoo Group.
Marty Lee, one of the original JET authors also maintains a JET page which contains a lot of useful information: Marty's JET pages
When using JET for the first time, or initially setting things up, it's important to get the core framework running first, and to get comfortable with using JET before adding and configuring additional modules. Marty Lee wrote a good JET Primer here
Marty also wrote a quick guide for Mirroring root disk using SVM
You will find a tutorial about Jumpstart Enterprise Toolkit at http://www.c0t0d0s0.org/plugin/tag/jet