Mine is simple, only handles one possible Rallypoint ("Mobile" spawnpoint) at a time. Never had a need for anything more complex so never bothered to really advance it. Feel free to do whatever with it. I add the action using 3 lines in the onPlayerRespawn.sqf to check if the respawning player is of the correct role to receive the action. This script also benefits from having an object near your base named baseFlag which will allow you to teleport to the rallypoint from that object.
if ((typeOf _unit) == "rhsusf_usmc_marpat_d_grenadier") then {
player addAction ["<t color='#FF707E'>Deploy Rallypoint</t>", "Scripts\Rallypoint.sqf", "", 0];
};
http://pastebin.com/zwqAk3FN
---------------------------------------------------------------------------------------------------------------------------------------------------
If you want to want to go with a more official FOB type thing where you are actually building a base then you could also go the extra mile and add it as an ALiVE recognized objective using cjb_addObjectiveToSides off the wiki . Here is a script I used in the past to add an objective via mapclick. Just add the action to an object and then define cjb_addObjectiveToSides somewhere such as the init.sqf.
http://pastebin.com/SWucXsMs