[Rails 3.1] How to create a (not typical) gem?

Hi guys,

I've got problem with creating gem in Rails 3.1. It's not typical gem.

1) First of all I'd like to automatically run this gem (always) with
other application which have it installed. I know that init.rb is
deprecated, but how can I use config/initializers in my gem directory?

2) Secondly, my gem have to do a very few things with file and directory
in my app. So should I defined this tasks in *.rake file in lib/tasks/?

3) Last one, how can I integrate this stuff in one single gem? Using
build or package_task?

I will be grateful for your help.