Thanks to Jonathon for giving me the dimensions of a Martin D40 dovetail to try this out.
This is parametric to you input the width of the dovetail at the top at the wide side, the width of the dovetail at the top narrow side, the depth where the dovetail ends (starts to round over), the width of the slot at that same point (where the dovetail starts to curve at the bottom of the slot), and the height of the dovetail itself. The parameters are currently set in inches to 1.84 for the width of the dovetail at the widest point at the top, 1.64 for the width of the narrow side of the dovetail at the top, 3.3 to where the straight dovetail ends, and .406 for the narrow width at this point. Print it and slide the jig up from the narrow side of the dovetail to hold your shims in place while they glue.