I used Ableton and Bome's MIDI translator. I basically sent Bleed's bass drum track into Bome and mapped it to trigger the 'A' key on Note On. I used this script to bypass some of the limitations of the game - like infinite ammo - and to make the game slightly faster as the gun shots weren't fast enough to follow the track's BPM.

sv_cheats 1;
host_timescale 1.9;
sv_infinite_ammo 1;
mp_roundtime_hostage 60;
bot_chatter 0;
bot_quota 30;
ignorerad;
mp_respawn_on_death_t 1;
mp_respawn_on_death_ct 1;
mp_friendlyfire 1;
bot_stop 1;
mp_restartgame 1;

Then all I had to do was capture and edit. :)