It's that last guy at the top that keeps capping you. The last outhouse has 3 enemies inside, one with a shotgun. Best to lead him and his companion down the stairs into a wider area to keep from getting blasted head-on with the shotgun. Weapon of choice is the Spaz. All I can suggest after taking care of the first two is take your time going up and see if you can locate his position before heading all the way up.
Chris N STAFF has played this game a good bit so he may be able to give some tips. As for Jamie's code, it could be it has to be done in a specific spot but he neglected to say. I'll do some looking around and see if i find that particular sequence elsewhere. It's also possible that code only works with the NTSC version of the game and not the PAL version.