Why exactly would the WSDL's be different? If you mean they use different locations you can use constant to specify where the server is located. This way you can have your development application using all the development webservices and on production you can enter the constants in your application.conf so that it uses the production servers. You can also do this with usernames and passwords.
Though this does mean that the WSDL has to be the same, just pointing to different servers.
The WSDL is only used to download what the different webservices do and require. Once you have this you can use the Location Constant in your imported webservice to point it to a different server that uses that same WSDL to actually call the webservices.
What exactly changes in your wsdl or what do you want to change for both environments? Because all url's, usernames and passwords can be configured in the modeler and in the application.conf as well.
So anything I can think of is configurable. Like Robert says imported webservice url's can be configured using constants. Just define a constant which you set with the url for your development/test webservice then you have to configure a constant in the application.conf of your production server something like this:
The name of the constant in the modeler is: WSURL_webserviceHolidayCheck This is line should be added to the application.conf Constant_WSURL_webserviceHolidayCheck = http://www.27seconds.com/Holidays/US/Dates/USHolidayDates.asmx
Furthermore you can change the url that is shown in the wsdl as location for the port bindings. That url should be the url where your client applications can call the webservice (without the /ws/wsdl stuff) This property should already be in your application.conf
ApplicationRootUrl = http://my.first.application.com/