With the declarative client-side binding you cannot pass any additional arguments, as the RadListView control does not know what arguments you need and from where to get their values automatically.
Instead, you should use manual data-binding where you can make an AJAX call to the web service with the needed parameters and assign the result using the set_dataSource()
Programmatic client-side binding of RadListView is demonstrated here:
The example uses page methods for binding, but the only difference is that you would need to modify this part of the script to call your web service, the logic for extracting sort/filter expressions is the same.
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