The one weakness of the radial arm saw it that it won't do fingerlap joints. On a table saw it's straight forward, install the dado head and cut the fingers holding the work vertical against the miter gauge. It's impossible on a radial arm saw, which is what graces my shop.
So, can you do them with a router? Yes. First you need a router table, something all true router fans have or make sooner or later. Mine has a 3/4" plywood top and the router cutter pokes up thru the top. With a fence to guide the work it's a poor man's shaper. The work is 5/16" thick, a straight 3/8" cutter sticking up 3/8" makes nice 3/8" by 3/8" fingers.
For the fingerlap joints we take the top off the router table and put a 3/4" dado across the top to accept a miter gauge. Used the miter off the band saw. Needed a couple of passes and a shim before the miter gauge slide freely. Then we put a finger in the miter gauge to space the fingers and go for it. Works. Good fit. Knock off for happy hour feeling very organized and wood crafty.