I did what you said, pressed out the metal sleeve first and then pressed out the poly outside. I rented this
kit from advance auto to do it. I chose this kit because of how small the clamp was. I took off the little cylinder piece that goes on the end of the screw and just used the screw to press it out. Then I did the same thing with a 19mm?? socket that went directly onto the poly part of the pushing and pressed it the rest of the way.