[Login.Register] accessing placeholder 'confirmurl' data in (post) hook?

Maybe somebody has a quick pointer in the right direction here:

Within Login.register hooks I can access most of the things I would usually need (form fields, password, hashed passwords etc). I just can’t wrap my head around how to access the data for the activation link which is set in the [[+confirmurl]] placeholder.

Did I miss something and it is actually easy to accomplish?