The Vendor of: can be created by creating two custom profile fields that only admin can see and edit.
One profile field for the link name and one profile field for the URL. You will be able to add link name and url via acp /member profile, your members will not be able to edit this.
You will then need to add code to postbit/postbit_legacy for it to show.
If you need this for vb 3.8 board, I will give you the code needed to accomplish this.
vb 3.8
I would love if you could help out with making that vendor of: module. Would I also be able to change the color of the text? I will donate you some bitcoins as thanks for help.