It's pretty easy.
- Install Gluu Server with Shibboleth. https://www.gluu.org/docs/gluu-server/4.3/installation-guide/install-rhel/
- Migrate your SAML cert into Gluu Server: https://www.gluu.org/docs/gluu-server/4.3/admin-guide/certificate/
- Create Trust relationship: https://www.gluu.org/docs/gluu-server/4.3/admin-guide/saml/