Fabric inlays are pretty simple actually. It is best to use silk or cotton fabric.
Tape off the inlay area as if you were doing a cut lap (because you are doing a cut lap actually)
Lightly spray 3M Super 77 spray adhesive on the blank and ROLL out the fabric, making sure to get rid of any wrinkles along the way. You can iron the fabric first if you want...
Laminate and let the resin soak through the fabric.
When the resin is tacky but not fully cured run a razor blade along the tape line and pull the excess off. Depending on the cloth it might be hard to see the tape so you can make a template first and scribe the line on the fabric before cut lapping.
You can push the edges of the fabric slightly into the foam with a popsicle stick to get it flush so no air bubbles will happen at the seam as you laminate the fiberglass over it.
Not difficult at all.