VERY IMPORTANT: If you have custom changes that you have not committed or patched out, you want to do that first! If you follow these steps without doing so, you will likely muck things up.
Okay. Let's say you've been running your Dreamwidth install and you want to pull down the latest and greatest in fixes. This is pretty easy.
cd $LJHOME bin/cvsreport.pl -u bin/cvsreport.pl -s bin/cvsreport.pl -s
Yes, you do it twice. If the multicvs.conf file changed, then the first one pulls that file in, and the second one will notice whatever changed according to that file. 99% of the time once is enough, but every once in a while... so it's a good habit to have.
bin/upgrading/update-db.pl -r --innodb --cluster=all bin/upgrading/update-db.pl -r --innodb -p bin/upgrading/texttool.pl load
That's the most of it. Of course, in a production environment, this whole process is not too recommended as you never know what kind of code you're going to get. But for the most part, it's fairly straightforward. (And if you're doing development, this is generally safe.)