Use composer to install bundle in custom directory

I see there is already a question but it did not answer the question

• How can I install a composer package into the /src dir?

How can I install a bundle in the /src directory?

Reason I would like to do this is for development and deployment, so

• I don't have to check in Symfony's base code into my subversion repo
• I could use Composer to deploy

Looking over the Composer docs some more I did come across this:

• http://getcomposer.org/doc/04-schema.md#config

vendor-dir: Defaults to vendor. You can install dependencies into a different directory if you want to.

Could I set this at a Bundle level? or is this for the overall install?

• https://github.com/composer/composer/blob/master/res/composer-schema.json