Hi Kikkerking,
This can be mostly done with template edits.
I'm not going to bother with the fancy popup effect, but here's how to use MyBB's popup menu to achieve a similar effect. Modify the following templates like follows:
postbit
Find:
Add under:
Also find:
Replace with:
postbit_pm
Replace entire template with:
postbit_www
Replace entire template with:
postbit_find
Replace entire template with:
postbit_email
Replace template with:
Also, open up /inc/functions_post.php,
Find:
Replace with:
That's pretty much it.
If you have MyPlaza installed, and want a fade effect, in the above code for postbit, replace:
with
Note that, since this removes the buttons from the bottom of the post, it has the side effect that if a user has Javascript disabled, they can't directly access the links from the post. Meh, vBulletin does that anyway, so it shouldn't be an issue
Hope that helps.