Here is the documentation of my next step: driving the LED display. The design and the C code were not really difficult; the steps to put the results here were.
As I noted before I use a PIC 16F887, but CadSoft Eagle didn’t have this component in its library, so I drew a 877 which is pin compatible. Now I wanted to get it right and so I started my own library. Copying the 877 to it and then renaming it to 887 was simple enough. The next step was to get my 4 digit 7 segment display (datasheet in PDF) in Eagle. I did find a 3 segment display that came close and it took me a bit of time to add the fourth digit. Now my custom library contains two components!