Before you do ANY tweaking of the CIS, check for vacuum leaks. Vacuum leaks can come in many forms and is VERY detrimental to your bunny's health. Vacuum leaks can come in many forms. 

• There's the ever common loose or busted vacuum line. Don't forget to check the lines going through the firewall into the air vent control box and the one going to the vacuum canister. Check the big lines too, like the one that goes to the A/C idle regulator.
• There are injector O-Ring leaks. Yes, these leaks can be just as bad as hose leaks. Buy a set of four O-Rings and pull them out and check them and go ahead and replace any hard or broken ones! I know in my car, right when I shut her off, I can here a slight hiss in the #1 injector. This does not belong here. This needs to be fixed! And, hey, while you're at it, check the spray patterns now, too!
• My not so favorite: The gasket leak. These suck because you usually have to bust out a can of carb cleaner to find these. Spray the carb cleaner around gasket areas and if the idle goes up, you've found the leak! Areas can include, the throttle/intake or the intake/head mating surfaces. Not fun to fix, but still a necessity to eliminate! Use some (not a lot!) RTV in conjunction with the new gasket.

After all of your vacuum leaks are nipped in the bud, you can move on to timing. Timing is easy. For those who know how to time, I'll humor you with the no-proper-tools-available way. For those who don't know what timing a car is about, I'll let you read this first, but then I recommend you proceed to the "go to Auto Zone and buy a timing light for $50" way.

All of your VWs have marks on the rotating parts to denote 0° TDC. The cam has a dot that lines up with the valve cover. The flywheel has a notch that lines up with the center of the hole on top of the bell housing. The distributor has a slash that lines up with the rotor. Line all of these up and your car is at 0. No advance. No retard.

In a pinch, I've put the car in 5th gear (with the car off!) loosened the distributor and pulled the car forward until the advance mark on the flywheel appeared in the little timing hole. I then turned the distributor until the hash mark lined up with the rotor and tightened her down. If your flywheel notch is at 3° or 5° or whatever, now your distributor is at 3° or 5°. It's probably good for keeps or at least until you can get your hands on a timing light, but it DOES work accurately!
 

You'll need to muster up some pieces for this, but this is a handy tool to make to have around. A VW fuel pressure gauge. I've worked hard on this fuel pressure segment that shows how to make a fuel pressure gauge and how to read it. Using the pressure gauge you can determine if your pump is good, your control pressure regulator is clogged and more.
 

For this you will need to locate your "lambda" test port and you'll need to buy a dwell meter. Below, you see where I've located the lambda test port on an '82 Rabbit. US Rabbits have the lambda test port behind the cold start injector. A Scirocco will have it on the other side of the intake manifold, just to the right of the coil.
 

A closer look reveals the size and shape of the test port.....
 

On my cheapo analog dwell meter (which is all I need, since this is the ONLY thing I use a dwell meter for nowadays) I have clamped two wires that are just the right gauge to fit inside the receptacles on the test port. Red into blue wire on test port (positive) and black into the black wire (negative). I set the dwell meter to 4 cylinder and crank the car up.
 

With your dwell meter plugged in and the car idling, you will see the needle on the meter bounce. An idle location for the needle to bounce between is 40 and 50. If the "bounce" is too low, say between 30-40 or lower, then your bunny is too rich. If the "bounce" is too high, say between 50-60 or higher, then your bunny is to lean. If the needle bounce covers a range greater than 10 (say a bounce between 25 and 40) then you have issues elsewhere. Check all of the above issues (pump, vacuum leak, etc.)

If your bunny seems to be too rich or too lean AND ALL OTHER THINGS ARE TAKEN INTO CONSIDERATION (pump, filter, vacuum leak, etc.) then (and only then) you can adjust the above readings with your 3MM hex wrench. Located between your fuel distributor and your flow plate on the lid of your air box is a hole. The hole is 4MM in diameter. This hole may be plugged. If so, find the plug and screw in a very small sheet metal type screw and pull the plug out. Beneath this hole (where you can not see) is a 3MM set screw that will adjust your mixture. Turning this screw clockwise will make the mixture richer, while turning the screw counterclockwise will make the mixture leaner. I recommend turning the screw by half a turn at a time, removing the screw, accelerate the engine and checking your dwell meter. Repeat as necessary. Once the dwell is hovering in the ideal range, adjust the idle accordingly (if necessary) with the 7MM "bolt" located on the backside of the throttle body and check the dwell again. Repeat if necessary.