You can buy any 'spot light wiring kit' from eBay/Halfords for £10-15. It will come with wiring and probably a relay.
You just take a direct, fused feed from the battery or another thick 12v constant supply somewhere in the engine bay.
I did this years ago on a 206, can't see how you need VCDS as this should be totally independant to any control module (depending on how you wire it though).
If you Google for a guide, it will apply from any car as this is a seperate circuit you're putting in. It only gets complex when you start taking a switched live, tapping into sidelights etc.
In my old car I just had them wired direct to the battery, and used them whenever I needed but had to remember switch them off with the ignition off (battery feed = lights stay on until switched off manually). Make sure you get a switch with a neon/light indicator.
I'd also suggest you get the fog connector plugs and a few inches of wiring to solder onto as it makes a solid, watertight connection.
When I did it I ran the wiring straight into the switch which was a 205 GTI fog button, there already was a dash cutout for this anyway. This button had a relay built-in.
In my opinion, I would look into doing it properly as a retrofit. I know it'll be much more expensive but in my old car I hated the DIY way of doing it and ended up fitting it via the car wiring (process similar to a Golf).
