Знаю этот плаг. У самого стоит. короче: Устанавливаешь плагин в ...Steam/SteamApps/common/left4dead2/Left 4 Dead 2/addons/sourcemod/plugins
ЭТИ КВАРЫ ПРОПИСЫВАЕШЬ В server.cfg (...Steam/SteamApps/common/left4dead2/Left 4 Dead 2/cfg)
zcs_enable 1 // Enable/Disable Zombie Character Select plugin.
zcs_debug 1 // Enable/Disable Zombie Character Select debug log.
zcs_respect_limits 1 // Respect server configured z_versus limits.
zcs_show_hud_panel 1 // Display infected class limits panel.
zcs_count_fake_bots 1 // Include fake infected bots in limits. (REQUIRES respect_limits 1)
zcs_switch_in_finale 1 // Allow infected class switch at finale stages.
zcs_allow_last_class 1 // Allow player to select previous infected class. (REQUIRES respect_limits 1)
zcs_allow_last_on_limit 1 // Allow player to select previous infected class when limits are up. (REQUIRES respect_limits 1)
zcs_allow_class_switch 1 // Allow player to change their infected class.
zcs_allow_cull_switch 1 // Allow player to select class when out of range of survivors.
zcs_allow_spawn_switch 1 // Allow player to select class after returning to ghost from spawn.
zcs_select_key 1 // Key binding for infected class selection. (1=MELEE, 2=RELOAD, 3=ZOOM)
zcs_notify_key 1 // Broadcast infected class selection key binding to players.
zcs_select_delay 10.0 // Infected class switch delay in (s).
zcs_cooldown_enable 0 // Enable infected class restriction timer after player death. (0=Disable timer) (REQUIRES respect_limits 1)
zcs_cooldown_delay 0 // Time before infected class is allowed after player death in (s). (0=Use director spawn time) (REQUIRES respect_limits 1)
zcs_lock_delay 0 // Time before infected class switching is locked in (s). (0=Disable lock)
И ВСЕ.
Здесь настроено именно так, как тебе нужно. Смена класса Правой кнопкой мыши)