Requires a 2 Dummy accounts
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 ctf_2fort; hostname "boost"; sv_lan 0; sv_cheats 0; (I had to input this twice to be detected on my LAN for some reason)
That will create your match. Choose Heavy on the Red Team. Then type the following command:
mp_teams_unbalance_limit 0; mp_idledealmethod 0; mp_idlemaxtime 0;
Put one Dummy account on your team and the other on the opposing team. Make the one on your team a Medic. Have the other account damage you and use the medic to heal you. You should get this fairly quickly.
This can be done easily in MP as well using the same method. You just wont be in control of when the damage stops so you will need to keep yourself alive.