With your SG leader character, use
/sgpasscode passcode
Make sure your passcode is word(s) related to your sg name (unless you want it weird for some reason)
Take note of the response from the game, as it tacks on a hyphen and a number to your passcode.
Then once you have it, use:
/macro Base "enterbasefrompasscode passcode" on any character and they will pop right to the base.
You can use the macro_image stuff from my post above if you want to get real fancy!
/macroimage Veteran_TeleportBase is the icon for the one we already have
Examples (and Nod is happy for you to use their bases to get around).
/macro_image InherentBase_Furnace TheProject "enterbasefrompasscode TheProject-16"
First room on the right has teleport beacons to all blueside locations!
/macro_image InherentBase_Anger NOGOOD "enterbasefrompasscode NoGood-179"