Unable to use method GET

Here's the error message I'm getting for my SetUserSettings web service method.
Request format is unrecognized for URL unexpectedly ending in '/SetUserSettings'.
When I look at my webservice in the helpful IIS screen I notice that POST is available but GET is no where to be found.  I tried to edit my web.config file to add the GET protocol, but VS2008 was unhappy with me making modifications to this file.
Any ideas on this?
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