Never tried that approach. You can try and see what happens. Always revert back if it doesnt work.
You will need to install SimPilots phpvms 5.5.2 version. Than you will get some errors. Big headache. If your site is still working on tpl version, I wouldn't change it. You can always download the skin. Change the files to .tpl and see what happens. I can't really help you. My server wont load the current phpvms version.