You don't need any jigs, calipers, dial indicators or custom machined super flat plates;
All you need is an understanding of what you are hoping to achieve, how to achieve it and a block of wood and a big hammer.
Cut the block of wood, examine it.
Smack the table with a hammer to adjust it. ( if its an expensive saw, use the block of wood in between the hammer and table)
Rinse and repeat until it cuts as accurately as you want it to.