Find a piece of scrap which is
w) roughly the same width as (the distance between the edge of the plate of your circular saw and the blade), say 5 inches,
l) 24 inches long (the distance between the first and last slot) and
t) 2 1/2 inches thick (the difference between the minimum and maximum depth cut).
Now taper this down (along its length) so that the width and length remain the same, but the thickness reduces from 2 1/2 inches (on one 5 inch edge) to zero (on the other 5 inch end).
On the 5 inch by 24 inch face, draw 24 gauge lines, 1 inch apart, parallel to the 5 inch edge. The guide wedge is now complete and ready for use.
Set the depth of cut on the CS to the maximum slot depth and make the first cut. Check the depth of the slot and adjust if necessary. Leave the depth at this setting for the remaining cuts.
Before lining up the CS for the second slot, put the guide wedge on top of the workpiece, slightly to the left of the second slot (so you don't cut through the guide block), long edge parallel with the direction of cut, thin end nearest you, with the first gauge line aligned with the edge of workpiece. Cut the second slot. It will be 1/16 inch shallower than the first cut.
Move the guide wedge towards you, so that the second gauge line is aligned with the front of the workpiece and move it just to the left of the third slot, then cut the third slot.
Rinse and repeat.
The more cuts you make, the thicker the wedge at the front of the workpiece and so the shallower the cut.
At some point, the part sticking out over the edge of the workpiece will be heavier than the part still on top of the workpiece, and it will be ready to overbalance, so just spin it round 180 degrees and start pushing it back in again - be sure to mark which slot you are on before you start this move.
Basically, it just a taper which lifts the base of the CS by 1/16 inch for every 1 inch it is inserted.
Each cut will be very, very slightly shallower at the back than at the front, but we are probably only talking a few thou.
To change the increment to 1/8, either mark only 12 guide lines 2 inches apart, or mark all 24 but only use the even-numbered guide lines.
This is just theoretical. I haven't built one before, but I think that its should
work. If you try this out, please let me know the outcome.