I havnt done it but I have looked into it. Search my friend, there are threads devoted to it. The trick to doing it is to pull the valve core and pour them in that way.

Speaking of searching, I went as far back as page 34 looking for your frame height. I found a post where you said it was at 26", however I am pretty sure you have adjusted your springs since then. So what is your frame height sitting at now? Any idea on how much up travel you have?

thanks, I will have to look around a bit and see what I can find.   well I dont think I have adjusted the springs since then but I have taken the 2" body lift off which made a huge difference in lowering the COG.  Currently with the tires aired up to 25lbs I am at 25.75" to the frame, 23.25" to the skid plate and 13.75" under the diffs.  It feels very comfortable on the trail and I have had the stock tip-o-meter up to almost 45 degrees without going over.  I feel alot more safe and in control of this rig compared to my last one. For up travel (at ride height) I am sitting 2" from the bumps in the front and 3" from the bumps in the rear.  But that is obviously not an accurate measurement of how far the tire will actually travel up, because the tire is farther out on the arc of the axle when flexing. Most people look at my setup and think my suspension must not move much, but it works excellent.  The springs sit flat which allows me to be low to the ground with 40" tires, and I am loving that setup. I had to setup the front bumps where they are because without them the steering links would rub really hard on the top of the front leaves.  The rear bumps are setup to stop the tire about a quarter inch from rubbing the inner fender.  Its been working great so far and I think I have only been lightly stuck twice ever since I have been wheelin it.