You can set up (and use) a LiveUpdate Administrator server, but beyond that, you can't daisy-chain SEPMs to pull from each other, which is what it sounds like what you're looking to do.
If you do go down the route of using LiveUpdate Administrator, you *must* put LUA on a different machine than the SEPM...there is massive disk I/O involved, and we've found putting the two of them on the same physical hardware (including in VMs on the same physical host) causes issues.
Realistically, though, with the huge improvements made with GUPs in RU5...there's not much need to have remote SEPMs. You might want to (if you haven't already) look into configuring clients at remote sites to pull from GUPs in the remote sites.