Requesting help finding a guide

[IRQsRFun]

I am hoping to use gentoo to alow myself to pursue my curiosity by looking at and possibly modifying source code for various packages. Are there some guides showing a very simple example showing how to do the following (I do have some ideas, but I am sure they are non-optimal):

1) Obtaining source code for a simple package, modifying the behavior, rebuilding and testing.
2) Restoring the package back to original state (official gentoo ).
3) strategies to allow switching between the two as I choose.

I am looking for a newbe level step by step description assuming a standard configuration (not customised much). Once I can do this, I think I can build on this. I am trying to avoid asking too many silly questions, but I am not aware of any user groups close to where I live.

Any help would be appreciated.

[steveL]

All you need to do is use a local overlay and follow the patch guide, in a nutshell. #gentoo-dev-help on irc.freenode.org is the place to get more help. See http://www.gentoo.org/main/en/irc.xml for other channels that are available.