That's basically the same idea, but the block and axlestand under the wishbone worries me. I keep the wheels on the the car, and lower it onto the four spare steel wheels from my sister's Morris. You have a pit, so could leave the car on the ground. Slacken the camber bolts enough to move the alignment with a prybar(I like the jack handle), and crawl under the car to tighten them. Another pair of hands makes this even easier/quicker.
I don't have the patience to adjust the front and rear toe settings with minimal equipment, especially as large adjustments affect everything else. Getting the camber correct with the front wheels parallel by eye means that any idiot with the 4-wheel alignment gear can get the rest of it right in minutes. That's easily worth the £50 to me. It's not as if it needs doing often.
Are you sister's wheels supporting the car under the body or under the wishbones? If under the body, it sounds like how 'Wheels in Motion' Chesham do it, with suspension unloaded.
Terry, they are under the Omega's wheels, effectively replacing the ground - from post #12
the old wheels are placed under the car's wheels so that the full weight is on them. If I were supporting the body I would just use axle stands. This gives me enough room(they are about 4.5"
wide high in this use) to crawl under the car with an 18mm socket and spanner and tighten the camber bolts, or adjust the tracking, with everything loaded at ride height.
With the use of a pit or 4post lift, such ghetto methods wouldn't be necessary. But I can't dig a pit, or install a lift in the street!