Install/Update scripts in ruby gems

Hello There

I’d like to create a ruby gem package (currently using newgem) which
works as a linux tool. It’s configuration should be located in /etc/ and
so on. So I need to include a setup-script into the gem, which generates
initial configuration files and stuff. And, of course, update scripts
which migrate config files from a specific version to another.

Do you know any approach how this can be done in a simple way? I’d like
to have something like rails migrations where i can specify an update
task from 0.0.1->0.0.2 (for example) which will be executed when using
‘gem install’.

Thank’s in advance
fatnack