you can't..
SME is a NT style domain controller, not an AD one..
if you need such features and your clients support old poledit scripts, you could try to find it, install on a windows client and the use it from there..
BTW, even if SME were an AD DC, it would not have any client/domain policy editor feature, because they are windows client related, so the best way is to use the right tools (on windows)
HTH