Yeah it can be a bitter pill to swallow when you buy a cable but it is an excellent tool and if you have a car which is out of warranty almost invaluable - you'll recoup your money back first time you have a problem.
Generally if you can post up a scan somone can point you in the right direction.
In a more diverse example I've coded somones car via MSN/Remote Desktop as they had a cable but weren't sure on what to do.
Stu.
A4 3.0 TDi S-Line Quattro, 7 Speed S-Tronic, Quartz Grey, 19" Twin Spoke Alloys, Alcantara with Silver Stitching & Heating, Nav High, B & O, AMI, DAB, Parking Advanced & Rear View Camera, Advanced Keyless Entry, LED Interior Light Pack, Hill Hold Assist, Heated Electric Folding Mirrors, Through Load.
Previous MY11 S3 Sportback Black Edition, S-Tronic, Ibis White.