On a similar subject, how do you cut into the inner corners on the cab (the corner between the monitor and marquee)? Should you just do it as best you can, and then finish it by hand. Or is there some trick to it?
If you are talking about the slot cut, it should be no different.
If you are talking about cutting out the side panels, then a router is the cleanest method. A jigsaw could work, but if you are cutting two panels simultaneously, it won't work well.
Cutting the panels one at a time will allow the jig saw to cut better but then your cuts won't be the same. Of course if shape it by filing and sanding and then cover it with T-molding, perhaps the difference won't be noticeable.