I made 2 jigs for making the shoulder cuts & cheek cuts.
The downside is that the blade guard has to be removed to use them so great car is needed while using.
Shoulder cutting jig was made similar to the mitre gauge from 2 strips of 18mm ply 4-6" wide. One lieing flat on the table & the other upright so it goes well beyond the blade. A hardwood strip was glued & screwed to the underside of the flat part to fit in the mitre slot. Make sure the cross piece is at right angles to the slot. One pass through the saw makes the starting point for tenons. I fitted an adjustable stop block past the blade with 2 wing nuts & bolts & a slot in the jig. You measure the tenon length from the saw cut to the stop block.
Cheek cuts are made from by cutting some 18mm ply to fit both sides of the saw fence joined between with more ply. It is kept square to the table by fitting more ply flat on the table on the opposite side of the fence. A stop fitted to the high side (12"plus) nearest the saw blade holds it in place with a couple of slots cut from the top of the high side for holding the work with quich release clamps. Looking along this jig, it looks like 'h_'
This jig needs to be a slide fit along the saw fence.
The biggest problem I found with my el cheapo saw is getting the fence locked in the right place to make the cut.
This 2nd jig doubles as a panel raising jig for use on the saw by tilting the blade 10° - 15°
I hope that was some help to you Chronosoft.
One thing I forgot about in my original reply is that you slide the jig along by holding it on the fence side of the jig so your hands are away from the blade. The idea has been around for years. Modern jigs can be bought in USA with micrometer adjustments & are heavy steel for stability. Norm Abrams uses them all the time on New Yankee Workshop & says his cost about £60.