Why mix the different media?
Get a sheet of overhead material, cut the spot out of the image in you image editor, paste them to a new document much larger, print on the overhead material. Take a fine brush to each spot to pick up the now mixed to proper color, paint on the print. Now it's all the same ink, so it should age the same as the rest of the print. If you mix the media to another type, the spots will not age the same as the rest of the print.
You can try inkjet overhead material, but it will let the ink dry. Regular overhead material will not let the ink dry, so you will have more working time. You may need to glue the clear overhead material to a sheet of thin paper to get it to feed correctly (depending on the printer).
Also note that both of these overhead materials could leave inky spot on rollers and stuff, so pick the printed areas carefully, or clean your printer after the fix. Since the inkjet overhaed stuff lets the ink dry, it will have a finite life, the laser or other overhead stuff should be able to be cleaned many times for the next run.
Alternate might be some nice white (opaque) drafting film because the sensors in the printer will be able to detect the film. The drafting film also normally has enough texture to let the ink stick to the printed spot, smooth sheets might let the ink drip.
Alternate to all this is to take those "empty" ink carts and drain the leftover into bottles. Then use these bottles to blend the approximate color and paint from a palette.
But over all I suggest using the same media that is used for the print so that everything ages at the same rate.