Moving sources (base/ports) from /usr

[Ede Wolf]

Hi,

As the title implies, I would like to move everything src/build related
from /usr to a different folder, let's call it /import. And since it
won't be mounted permanently, I'd rather like not to use links. That would certainly work, but it's ugly. 

So I am looking for a more clean way of archiving this, but currently I am having trouble to find a
comprehensive list of the  variables, that would need to be set, and more over, where the proper place woulf be, to do so. 
More often than not it is not /etc/make.conf 

For MAKEOBJDIRPREFIX it is src-env.conf, but what about the others?

SRCDIR, PORTSDIR, WRKDIRPREFIX, DISTFILES, WRKSRC? Is that list correct and/or complete?

Is there any documentation providing a decent overview of the
environment (base as well as ports)? Or maybe anyone is running this
kind of setup as well?

Thanks for helping out

Ede