Custom product authentication using EBS framework & OID

Hello,

We are in the process of implementing SSO for EBS R12 (12.1.3) and have come accross a situation where there is a custom bolt-on application utilizing the EBS Security framework for user login & authentication.  The custtom application uses the packaged procedure FND_USER_PKG.validatelogin(p_username, p_password)to authenticate the user.  Although users still exist in the FND_USER table the authentication for SSO now resides in the OID repositiory.  My question is:  Is there an API that can be used to replace the one above that will allow the custom application to authenicate through OID but still use the EBS security framework (ie: responsibilities, etc)..