So, I managed to build a netinstall set, and got it to boot, but after entering my JSS username/password, I get the following error:
"Casper Imaging could not locate any drives for imaging."
This machine does have a working 10.9.3 install, currently running JSS 9.3, Imaging app 9.3 as well.
I've tried this on a physical mini (the one with the error above) as well as on a virtual machine.