(Also, please check out the development survey)
It is very convenient to create a couple of config files like these:
[general]
data-path=gitchain1.db
[api]
http-port=3001
[network]
port=31001
[general]
data-path=gitchain2.db
[api]
http-port=3002
[network]
port=31002
join=localhost:31001
Lets say you called them git1.config and git2.config, now you can start them as simply as this:
$ gitchain --config git1.config
$ gitchain --config git2.config