Use Custom Authorizer created outside Serverless Framework

I have created an API Gateway and Custom Authorizer using Terraform, outside of Serverless Framework. Using the docs, I figured out how to use the API Gateway I created in my Serverless.yaml config, but I am not able to figure out how to make use of my existing Custom Authorizer. I have looked at several of the Github issues and tried to emulate their solutions with no luck. Is it possible to use an external Custom Authorizer with Serverless Framework and have it be shared among multiple services? Please advise.

You should be able to specify the ARN of the authorizer you created in TerraForm using the arn param withing the authorizer config

arn: arn:aws:lambda:{self:provider.region}:{self:custom.environment.{self:custom.stage}.awsAccountId}:function:{self:provider.stackTags.product}-internal-${self:custom.stage}-