So the solution I found (based on @marc_s' comment) is adding another endpoint as webHttpBinding:
<endpoint address="rest" binding="webHttpBinding" contract="MyNamespace.IMyCometService" bindingConfiguration="UnsecuredWeb">
<identity>
<dns value="localhost"/>
</identity>
</endpoint>
Then calling the service from the third party software via http://localhost:54538/MyService.svc/rest