The only thing those links didn't give you was the I2C accessible Address and Register Map for the SRF08 which is what you need to play with PBP's I2C commands. A quick dogpile search found something more useable here...

http://www.robot-electronics.co.uk/htm/srf08tech.shtml

From that you can see the default address is $E0 and you've got 36 registers to play with and access...

So use your I2C command like this...

SRFAddress var byte
MyByte var byte
SRFAddress=$E0
.. ..
I2CRead Datapin,Clockpin,SRFAddress,$00,MyByte

This should read the Software Revision (Register Address $00) into the variable MyByte. From that you can work out how to send the appropriate I2CWRITE command to the SRF08 to initiate a ranging, wait 65mS, and the read back the results with an appropriate I2CREAD.

Melanie