For this instructable I will be using the BS2e but any member of the BS2 family should work.
Step 1: Charlieplexing: What, Why, and How
Why use charlieplexing with a Basic Stamp 2?
---Proof of concept: Learn how charlieplexing works and learn something about the BS2. This may be useful to me later using faster 8-pin chips (only 5 of them will be i/o).
---Useful reason: Basically there is none. The BS2 is far too slow to display without noticeable flickering.
What is charlieplexing?
---Charlieplexing is a method of driving a large number of LEDs with a small number of microprocessor i/o pins. I learned about charlieplexing from www.instructables.com and you can too:
Charlieplexing LEDs- The theory
How to drive a lot of LEDs from a few microcontroller pins.
Also at wikipedia: Charlieplexing
How can I drive 20 leds with 5 i/o pins?
---Please read through the three links under "What is charlieplexing?". That explains it better than I ever could. Charlieplexing is different from traditional multiplexing which needs one i/o pin for each row and each column (that would be a total of 9 i/o pins for a 5/4 display).