OK, here is a brief write-up of how I completed the Slimline conversion. I suspect these directions will work for a reasonably sized Dish Network dish as well.
First, as mentioned previously, the LNBF (the thing at the end of the arm with a few circular plastic things) is not compatible with the Outernet satellites. You need to acquire a KU Band PLL Linear LNBF and a universal LNBF bracket. I purchased both of these items on eBay for about $20 from seller "ke4est" - however you can obtain them from whomever you like. The universal LNBF bracket looks something like this:
You will next need to make some adjustments to the Slimline dish to configure it for single satellite use. You can do these things while you wait for the parts above to arrive.
Your Slimline is probably set at an angle so that it can focus on multiple satellites at once. You will only be focusing on a single satellite, so we want the dish to be horizontal. To accomplish this, loosen the 3 bolts between the dish and the mount and set the angle to 90 degrees:
You will then want to set the elevation. This varies from location to location. Go to dishpointer.com and put in your address. Select the satellite you will be using for Outernet - in North America this will usually be Galaxy 19. Make note of elevation, azimuth, and LNB skew. You can also use the map to make sure there are no obstructions between the dish and where you will point the satellite.
On the side of the slimline mounting bracket, there is an elevation scale. You will want to set this to match the elevation you made note of above. You will need to loosen two bolts on the outside left and outside right, and one bolt on the inside left, of the Slimline mounting bracket to adjust elevation.
Elevation here has been set for about 39.5 degrees:
It's now time to replace the LNBF. To figure out where to place the new one, I took a folded piece of aluminum foil, taped it to the support arm, and bent it to match the location and angle of the original center LNBF. I drew a red dot at approximately the center point of the LNBF.
I then removed the old LNBF and positioned the new one. I had to drill a 1/4" hole approximately 2 3/8" from the end of the support arm. I had to drill the upper part of the hole out a bit more to allow the square-shaped section of the universal holder's included bolt to pass though.
I used the foil to line up the new LNBF with the original. Adjust the height to center the new LNBF to the center point of the original LNBF. I also had to bend the LNBF holder forward a bit to get it close to the original angle:
You will also want to set the LNBF skew at this time. Use the LNB skew angle you made note of before and turn the LNBF until the 0 line on the LNBF until it lines up with the correct setting on the LNBF holder's scale. Keep the LNBF a little loose so that you can fine-tune this later. Note that the direction indicated on the dishpointer.com site is from the perspective of standing behind the back side of the dish.
The end result should look something like this:
Take the dish outside and sit it on the original pole. Don't tighten yet. Use a compass to point the dish in the direction of the azimuth (magnetic) that you made note of earlier. Slowly swing the dish back and forth and watch the Quality graph on the Outernet tuner settings page. Note that "Signal Strength" is pretty much irrelevant - you will want to pay attention to quality. The indicator might be delayed by several seconds, so make very small adjustments and wait for the results.
Once you have peaked the signal quality by moving left and right, tighten the dish mount down. You can then fine tune the dish elevation. The Slimline has a nifty elevation fine-tune adjustment - it's the long screw on the left of the bracket. Adjust this to best signal quality.
You can then proceed to adjust the LNBF skew, bend the LNBF bracket up and down slightly, and move the LNBF back and forward - doing each in small increments and waiting several seconds after each adjustment to see if the quality improved or not. Lock each thing down as you find the best quality.
If you can't find a signal lock, check that the new LNBF is positioned as close as possible to where the original LNB was. Check your cables, connections, make sure the LNBF skew is correct, and that dish angle is 90 degrees and the elevation is set correctly. Double check everything against the dishpointer.com site for your location.