Cognito User Pool with PreTokenGeneration trigger

I’m trying to spin up a Cognito user pool with a PreTokenGeneration trigger to modify some claims in the token, however it appears that CloudFormation doesn’t support that trigger type at the moment

Since the problem likely lies outside of serverless framework, I was hoping that anyone could suggest workarounds in the meantime, while using Serverless?

I posted the lack of the trigger type to AWS as well: