That's pretty much what I do, and I've surely done less of it!
I think the general rules are:
- Find the pins on controller leading to the matrix
- Figure out which of those are rows and columns
- Follow as much by eye as you can, and use the beeper as your sixth sense
- Draw a grid, label the columns and the rows, and populate the bugger one key at a time
- And do what Oldie says: keep the diodes out of it, bypassing them when dealing with those pins
I'd like to think there's a better way. Anyone?