Cheat mode (to the extent of using the console '~') does not work on these difficulty levels.
I have the steam version, thus can't compete, however I did get at time of 5:46, no use of *any* cards.

Ah, cool. I only ever played on the standard setting (I have the boxed version)

any tips to making a faster run?

Kill as little as possible and get to the exit ASAP? Also, doing practice runs might help..

exit doesn't appear until the enemies are dead.. afaik.

Yep. Painkiller is a game that gets very disappointed in the player when he delivers anything less than complete demon genocide.

Gah, I have the Steam version, guess I can't participate.

I bought the game and now I can participate in this contest, hell yes! I probably won't win, but whatevs.

First area. Kill everything, simple really. Try to be close to the door that unlocks and bunnyhop like mad to the second area.
Second area. Hop like mad and grab ammo, hop into the building with the stairs. Grab the amour and quickly snap shoot the guy that spawns above you. Kill enemies as they spawn after they finish hop down and kill the rest on the way to the door.
First area again. Kill the witch thingy.
Third area. Hop like mad to the far end and kill everything. You should be one shotting them in the chest.
Fourth and Fifth areas. Hop in kill everything, leave.
Sixth area. Memorise the spawn locations and how many spawn where. Kill everything.
Seventh area. Hop in kill everything, leave.
Eighth area. Hop into the first building, kill everything, leave building, kill stranglers, hop out.
Ninth area. Either kill everything in front of the church or head around the sides and take care of those spawn points first.
Tenth area. Head to the level end and kill everything as it approaches.

4:29?! I just got 6:59 :( In my defense though, I just played the game for the first time, pretty awesome. I hope that the rest of the levels have a bit more challenge though.

Yeah dont worry, the first level is kinda lame and straightfoward.
BTW, is 4:52 any good? It's the best i seem to be able to do. Doubt it'll stand any chance against the pros.

Well, after a bit of practice this is the best i managed 4:33, i know i could have done better if i had a bit more practice, but oh well. Seen here as a tiny pic cause of the file size limit.

OK, I want to clarify to be absolutely sure here, that I'm NOT flinging accusations around. I'm not accusing anyone of cheating, and I'm not saying that whoever wins this cheated.
However, that screenshot is not proof of performance at all.
Even assuming that people don't photoshop the numbers, which is quite possible, there are other ways you could easily get a very low time.
For example, I loaded up painkiller with powermad (a set of utilities to let you do all sorts of neat things). I could have toggled god mode, but it was even easier just to simply explode all enemies currently spawned at the press of the key. Running through the level like that got me an impressive time: http://baldurk.org/speedrunnin.png (also attached).
So I got a 3:00 time, and really I don't think there's anything in that screenshot that incriminates me. I could easily go back and do the same thing faster, and pick up more souls, ammo and gold. Most of the time I was just standing around waiting for the enemies to spawn. I could also get rid of the FRAPS fps counter, that was a stupid mistake.
So again, I'm not accusing anyone of cheating, but I think it's quite possible that people could - and I think it's important for people to know.