Personal Contact Form Alias

I have tried to make simple extension of pathauto module to generate aliases for personal contact forms. I have managed to get it working it working by adding checkbox to pathauto settings form and then inserting a condition into method createEntityAlias in class PathautoGenerator. I was not very satisfied with this solution since pathauto is quite complete module and such hack seems inappropriate.

Does anybody has any advice what would be proper way of addressing this issue? I have also tried with overwriting EntityTypeAliasBase but since contact_form is not an entity I had a lot problems so I gave up.