SEPM on RU5 can manage SEP MR4 cleints, But the question that you have that can SEPM on RU5 push a package pf MR4. The ans to the question is YES , if the pacakges for MR4 is already there in the SEPM Admin Tab under Install Packages.
This is only possible if it is an upgrade from MR4
.If it is a new /fresh install of RU5 you cant create MR4 packages as you can't add that packages in RU5 SEPM