http://www.project1999.org/forums/sh...ad.php?t=76962 (latest patch notes thread)
At the top of that thread, there is:
This patch contains new files. Please obtain the latest EQChanges V23 from the setup guide, or obtain the latest files via the EQEmu Launcher.
If you click the eqchangesv23 link, you should get a download option for eqchangesv23.zip. Download it. Extract it. Look at files.
Manually replace whatever files are necessary (making backups of the ones you remove in case you don't know what you're doing).
Hope that helps.