[O] Mark vacation days

[JRSS]

I tried to post to stackoverflow but I'm not sure it took, so I'm trying here as well:

I'm looking for a way to mark vacation days in my agenda view in different color. This would probably be triggered best by category (so when a header is marked as a vacation).

I found this post which is getting quite old, and he says it has been implemented into Emacs but I can't see it anywhere. It's based on Orgs ability to mark weekends in different color.

Ideally, I'd like to have different colors for day headers in the agenda correspond to different categories. Vacation is just the one prime example for that.

Does anyone know where I start getting something like this working? Programming is not my strong suit, but I can slowly wrap my head around some bits of code.

Thanks!