Yes this is possible. Please refer to the following blog post.
Also I'm attaching a sample implementation for a CustomEvaluator that extends the default SearchKeywordsEvaluator. It can be registered to Sitefinity the following way in the Global.asax file:
sender, EventArgs e)
Telerik.Sitefinity.Abstractions.Bootstrapper.Initialized += Bootstrapper_Initialized;
sender, Telerik.Sitefinity.Data.ExecutedEventArgs args)
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