Hello Ade, here goes.
It is dead easy to apply to the A2.
Step 1. Remove lovely A2 jack from boot and start at any wheel. Jack up wheel so just clear of ground,( chock wheels )
with valve at the bottom, remove valve ( with special valve cap in U/ Seal box ) to let air out.
Step 2. Knowing exactly the quantity needed remove bottle from box ( dont shake! - the fluid obscures the division marks ) snip end off the pointed nozzle, and push on tube. The trick here is to make the hole in the nozzle big enough to allow the fluid to flow easily, but not too big, but tight.
Step 3. Push the end of the tube over the valve, up end and squeeze the correct amount in. As you up end the bottle you will see that there is an air gap so you have to "measure" the divisions- you'll see. Remove tube, clean valve.
Step 4. This is where a compressor comes in handy. Blast a tiny amount of wind in to valve, to clear threads, refit valve core and inflate to correct pressure. Lower car to ground and repeat with other 3 wheels.
If you take your time making the right size hole in the tube/nozzle assy you can use the same one for every tyre. If it's a cold day it takes some time to sqeeze the fluid in !!!
After all this, drive the car for say 5-10 miles. It will feel like the wheels are WELL out of balance, but it will soon disappear. Mine took approx 6 miles to bed in.
I have access to a medium size compressor, but I imagine you could use the one that comes with A2. To clear the threads before refitting the valve core, a bike pump would do.
There are comprehensive instructions with every bottle of U/Seal.
I've done 4 cars now without any trouble; 2- Seats, 1 A2, and a Disco, and the bikes are next!
Just make sure that about the correct amount for your size of tyre ie 175/60R15 or 185/60R16 or 205/40R17, whatever.
Hope this of some help to you.
Regards John W. 2002 TDI SE