Creating Cloudformation changesets through SLS


Here is brief description of my issue:
I am creating AWS Codepipeline for deployment of my serverless application containing API gateway and Lambda funtion.

Here is how my Pipeline looks like:-
Stage1: Get the source code(buildspec.yml, serverless.yml , handler ) from Github
Stage2: Execute CodeBuild step that will create the Cloudformation changeset for the stack to be executed in later step
Stage3: Approval on the changeset
Stage4: Execution of change set.

I have separate roles for pipeline, CodeBuild and Cloudformation inside the template for the pipeline itself.

In the serverless.yml , I am running the following command
- serverless deploy --changeset Changesetname --stage $ENV
This is a basic command I got from the documentation. However, this does not have any mechanism to pass the role to the changeset.

Could you please let me know how to pass the cloudformation role to this command so that cloudformation assumes it while executing the changeset.