I would do it the same way I do all large packages - use wget to download a source tarball and build it on the Galileo. For example, Tomcat is available at:
Do note though that Tomcat requires Java be installed first. Build it the same way.
Yeah, realistically this this the best way for such packages at the moment.
I don't have them in the repo yet, that's why opkg gives you nothing. I do plan adding those, but the amount of interesting stuff Galileo generates overcomes my free time resources :-)
Ok, then I'll will try to do it that way.
I've added the mysql server and client packages into the repo. Right now it's just the version shipped with the Yocto version Galileo uses, so it's a bit old (5.1.40), but can be used if you just need the DB. I don't have the board with me right now, so feel free to post your feedback as to the installation and whether it actually works or not.