hack to show only the first post of each message to guest

[mcncyo]

I would like a hack that will show only the first post to guest and replace the following post with something like you must register to finish reading this topic.

something like what was made for vbulletin 2 located at
https://vborg.vbsupport.ru/showthread.php?t=53282

[lange]

I'm looking for basically the same thing...