I've developed some useful scripts (with some help from linuxquestions.org) to allow the hpgl based Roland engraver and milling machines. The ones I use are old but they use the same control set CAMM/GL or a close version or hpgl. The scripts have pop up screens to allow for enraver selection and speed settings. They work pretty darn good for me anyway in conjuction with coreldraw (wine),Inkscape and the roland 3d software that runs great in wine I can do pretty much anything I want.
Here is a quick web site I did to help anyone get it installed I know the site stinks I'm no web designer and it shows!
www.securetech-ns.ca
This can easily be used for any hpgl device and roland's vinyl cutters also. Very little editing would be needed.
Drop me a note if anyone finds it useful or improves on the interface by adding more options.
I always engrave at the same depth so "z" depth are not a big factor to me.
gary