Requires at least 1 Dummy account
Open the command console: ESC > Gear Icon > Under the keyboard tab select Advanced > Check off Enable Developer Console
Press the ` button to open the console and type:
map sd_doomsday_event; hostname "boost"; sv_lan 0; sv_cheats 0;
That will create your match. Choose the Red Team. Then type the following command:
mp_teams_unbalance_limit 0;
This will allow you to stack the opposite team. Then add a bots using the command:
tf_bot_add blue;
Put the Dummy account on your team and wait for the Bumper Car Soccer Game mode.
Put yourself inside your goal and use the Dummy account to bump the Bot into the other goal. The Horseman will spawn and he wont detect you or the bot in the goals. Let the Horsman kill the dummy account and just float to your character to respawn and then let him kill the dummy account again. Rinse and repeat.