Shifting into Lowrange with insta-trac

I was wondering if anyone knows how to switch to low range using an insta-trac floor shifter? I can switch to 4wheel high on the fly, but when I try to shift to low range, it sounds like something is rubbing in the transmission, I've tried to shift to low range in both neutral, and park, and the same noise occurs.
Is it normal for there to be a weird noise when going to low range?

Thanks

You slam it. I have a 96' Z71. I know that it sounds funny, but your not supposed to be gentle, the transfer case is designed to shift this way. All 4 hi does is engage the front diff and lock in the driveshaft. You can be gentle between 4 hi and 2 hi because your not changing the gear ratio. If you shift into 4 lo, here is what you need to do. If you are at a stop and in 2 hi with your wheels straight, switch to 4 hi and move forward (or backward) until you get it to engage. Then, once in 4 hi, stop, put truck in park or neutral, and then FIRMLY and QUICKLY move it down into 4 lo. I shouldn't have used the word "slam". That makes it sound as though you should just kill the shifter. No, your just supposed to use a little force and shift it into 4 lo. If you don't want to have the very distinct engagement clunk, I guess you could always turn off the truck and try it, but there are some times that you wouldn't want to do it that way. It sounds bad, but actually you will wear down the engagement teeth very quickly if you try and do it gently. Hope this helps. If any other 4 wheelin' people want to give their 2 cents on my technique, chime in, I'd like to hear your comments. -Chris