I've never used SheetCAM, so can't help you there.

What I'd do is draw duplicate geometry for the slots, and put them on a separate layer. Then just cut them by themselves first.
Your perimeter cut can then either go into the previously cut slots, or go right past them (if you edit the geometry).
Note that some CAM programs won't let you cut a 2mm slot like that with a 2mm cutter. You may need to enlarge it to 2.01mm
AN alternative is to draw a straight line down the center, and cut a "rough" slot on the line.

Hope this makes sense.