Changing a Web Reference URL at runtime?

Question

I have an inventory application that uses a web service for security authorization. I would like the program to be identical for each client, and have them have a config file that has contains the url for the web service. (eg. ClientName.myinventoryprogram.com/signOn.asmx) Is it possible to change this URL at runtime, even though it was added as a Web Reference to the project?