New SEP server in DMZ to download SAV files

I need advice please as not to famailar with SEPM. We currently have a SEPM server that downloads the liveupdates\definistions and a couple of child servers that download the liveupdates from the main SEPM server. Due to changes in our environment I now need to build a server in the DMZ to carry out the liveupdate\Definitions downloads whcih then distributes them to the SEPM server which then passes on to the child servers.

Can anyone advise what I need to do for this to work. I do I select Install Symantec endpoint protection manager or install an unmanaged client or is it something totally different?

Thankyou in advanced.