How to copy scripts?

If a website have got a custom script and i want to steal it, how can i do this? And is there any way to get the mysql data of vbulletin forum (which i don't own) and inject posts on a phpbb forum?

Only if you hack the server and if the code is not encrypted. Bad idea in my opinion. Just code the features of the script or hire someone to do that.

There are scripts to get data from foruns, then you just have to import the data.