I think thats a very cool project, to build the hardware for scanning the tape. You have to decide between an optical or mechanical detection. I prefer an optical solution, you only need a light source an 9 sensors. The size of the sensor could be a little problem, because you need 9 of them in a row. Maybe that your tape is round about 1 inch, so the distance of two holes in the tape is 2,54mm, thats exactly the grid of breadboards or hole grid pcb. At first I thought about light dependent resistors (LDRs) but it should be possible to use a LED as well:
http://hackedgadgets.com/2006/04/14/led-touch-sensor/
So you could arrange 9 LEDs in a row as a good light source and 9 LEDs as sensor.