Here is an example for Basic Stamp. They are using the MMA7455 in the SPI
mode and not I2C, apparently it can do both


https://www.parallax.com/downloads/m...tamp-demo-code

Not that you want to change devices, but as a side note. The ADXL335 accelerometer module
found on Ebay cheap, outputs 3 analog voltages which makes it really easy to connect to a pic.