Capturing with Fraps is extremely straighforward, it will use it's own lossless codec for initial capture, and you'll want to recompress it later on.
Setup is basically nothing, set Fraps to record at a suitable FPS and hit the hotkey, if your PC is unable to capture at your desired FPS, either lower your resolution in LFS, lower your capture FPS or set LFS at 0.5 or .25 (or .125) speed and record in a suitable FPS for speeding up later on, audio does become a problem when you record in slowmotion.
There's a "guide" here: http://www.lfsforum.net/showthread.php?t=219, it's pretty much right except there's really no need to limit the fps in LFS since Fraps will do it for you, and if you can record without using 0.5x speed, why not.
Edit: since you're using Premiere, don't bother with any of the VirtualDub stuff in the guide, if you need to speed up captured video do it in Premiere (200% speed for example).