but the wheels I want are 5 stud. How would I go about converting it?
You can do it with parts from a 5 stud mk3 but by the time you add the costs in, is it ever worth it.
And you will probably create more problems for yourself, etc.
There is a huge range of 4x100 rims that are f**king sweet, so tbh there is no point at all. I fit bigger brakes to my CL when I converted, but kept it 4 stud for a reason!