How do you setup cross-account IAM authentication in AWS MSK?

We have an AWS MSK Cluster setup with IAM Authentication in Account A. We are able to setup an IAM Role in Account A, and allow that role to be assumed by a user in Account B to allow a user cross-account access to the cluster. If we want to run something like AWS Glue for example in Account B that needs to run as an IAM Role in Account B, how can we setup cross-account access to the Cluster in Account A? For other services we would configure a service policy that allows the cross-account trust relationship. I do not see anything like this on the MSK Cluster resource. The only thing I can think of is to use SCRAM authentication with pre-shared user credentials in a secret. However, we really need to use IAM authentication for compliance.