PAM(Pluggable Authentication Module) in zlinux for bfagent

Userid(ex: testUser) is defined on zlinux system who can only su. it is not allowed to login thru console.
When build forge console trys connecting to buildforge agent installed on that zlinux server. It gives an error "Unable to set user account to unknown account".
How can we configure PAM for build forge agent so that testUser is allowed connect to build forge agent via build forge console