Possible to manually change links for threads?

[Inna]

Hi there, is it possible to manually change links of specific threads?
For example, site.com/showthread.php?t=123 and we just want this url changes to site.com/how-to-do-that.
Just some specific threads that only user-id 1 (and maybe other admins, not mods) may change or use it.
Requires modifying php files? Database tables?
I'm not sure what exactly to do.
Thanks in advance

[Dave]

If you only want to do it against a few threads, you can just write a few .htaccess rewrite rules (without redirect) that when a specific URL is called, they internally call a different URL.

However if it has to be more flexible, you're going to have to create a dynamic .htaccess rewrite rule and additionally modify some files (mainly showthread.php) which will take too much time/work for me to explain to you in a post here.