Actually, you can download a handbook with code examples from Hi-Technic's website here:
http://www.hitechnic.com/file.php?f=...lease_v1.0.zip
Also, if you're using ROBOTC, Xander Soldaat (who author's a 3rd party driver suite for ROBOTC) has some useful I2C guides here:
ROBOTC I2C Howto (Part I)
Using the ROBOTC I2C Test Utility