I'm assuming when you mean "re-installing" you mean installing NEW grommets. From my experience, once the racket has been strung, the grommets get flared and you can't reinstall it easily.
When installing new grommets, all you need is an awl or a couple of awls of varying sizes. A hair dryer is sometimes helpful, to soften the grommet to be able to stretch it a bit and to help remove the old grommet.
As for installing grommets, it's pretty straight forward. Align the grommet to the corresponding holes. Starting from the middle top is easiest. This video from YULitle (Mike), will show you some of the techniques. http://www.youtube.com/watch?v=1s4bH7T9sds