You may be getting tired of my clips from the manuals but here is another one. It doesn't actually tell you how to lube the intermediate shaft as I expect the job takes 3 arms and a circus trapeze but here is what it looks like. I need to do mine too...
Screen Shot 2016-04-21 at 16.44.32.png
Look at this:
http://www.redhummer.com/myhummer/steering_shaft/index.html
And this:
<b>Steering column:</b>
<p style="color:rgb(0,0,0);font-family:Arial;font-size:14.6667px;background-color:rgb(238,238,238);">The steering column (the steering shaft actually) has two u-joints in it. One is located a few inches from the steering wheel (under the dash). The other is located near the steering gear, under the hood (within about a foot of where the steering shaft passes thru the fire wall). The steering shaft also has a "sliding part" which allows the shaft to change length. This joint is located near the u-joint inside the truck, under the dash. Some, but not all, Hummers have a grease fitting here.
<p style="color:rgb(0,0,0);font-family:Arial;font-size:14.6667px;background-color:rgb(238,238,238);">
<p style="color:rgb(0,0,0);font-family:Arial;font-size:14.6667px;background-color:rgb(238,238,238);">
<p style="color:rgb(0,0,0);font-family:Arial;font-size:14.6667px;background-color:rgb(238,238,238);">Let me know how hard this was to do.
<p style="color:rgb(0,0,0);font-family:Arial;font-size:14.6667px;background-color:rgb(238,238,238);">
<p style="color:rgb(0,0,0);font-family:Arial;font-size:14.6667px;background-color:rgb(238,238,238);">
<p style="color:rgb(0,0,0);font-family:Arial;font-size:14.6667px;background-color:rgb(238,238,238);">Derek