I use my Trion, blade facing up, all the time.
To cut a hole, just support the board you are cutting through on both sides and leave enough space for the Trion to turn full circle.
Drill a hole wide enough for the jigsaw blade to get through, and cut from underneath, cut mark facing up, blade facing up through the hole, following the cut mark with the blade.
If you are just making a simple cut, lay the board over a bench or a board with some overhang on some sawhorses, clamp it, and cut it.
With just a little practice, you can follow just about any line you can draw.
Hope this may help
Greg