rocknbil - 3:56 pm on Apr 25, 2012 (gmt 0)
I have cornered myself **one time** doing this. I really do regret it. If you have a choice, find another way, now.
If not, document **everything** you changed and save it in a file somewhere easy to find, name it "wordpress-core-mods.txt" or something. You won't remember what you changed in the future. Also when updates come down, the line numbers will change, so the line number is not a good way to identify where the change now is. I did it like this:
around line 348, change this line (or chunk of code)
// whatever the line WAS
// what you changed it to
There really is no other way I can think of, and it's really a pain in the patootie. If you save your modified file and just replace it in the update, it may break Wordpress completely.
I'd almost rather put the code in an external and include it than do that again. :-\