Copy instant_respawn.smx to addons/sourcemod/plugins
Copy plugin.instantrespawn.txt to addons/sourcemod/gamedata
Notes:
Use the DoD Hooks version if you have it installed, otherwise it may not work. (SMX compiled against SM 1.3, requires dodhooks.inc to compile (Included))
The plugin creates an auto exec config located in cfg/instantrespawn_config/instant_respawn.cfg