Put the following in your crontab:
0 * * * * rsync -rtz rsync://rsync.nquake.com/nquake /path/to/nquake/files
Change /path/to/nquake/files to something like /www/nquake/ if that folder exists and is available through http.
Post the URL to your nQuake mirror in this thread and it will be added.
You can also give me your mirror information to me via e-mail (mpezar at gmail.com).
Please include the mirror's URL, its upload speed (e.g. 100 mbit/s) and location (city, country).