I am trying to get a mileage from 2 zip codes

EXAMPLE:
http://www.transystem.com/ptToPtMlg/ptToPtMlgCalc.cfm

I would like to do this from within a worksheet to achieve a mileage then be
able to use that mileage to formulate rates.

Any suggestions how the example was done and how do I go about doing
this.......

I know what to do with the rates once mileage is gained but I need to get
the mileage..

Thanks
David Poe