Patch management without write access to CVS

["Jesper Louis Andersen" <jlouis_(_at_)_mongers_(_dot_)_org>]

How do you manage patches to a project like OpenBSD without direct
write access to the CVS? To me, with the review proces in OpenBSD,
it seems to me that many of the developers push around patches
before they are put in the tree, and I like this approach. But what
are the tools used?

I can imagine that diff and cvs diff are used heavily, but it seems to
be expensive if you need a fresh source checkout all the time to just
apply some simple patch and test it. Is filesystem layering the solution
to this problem? I know that Pawel Jakub Dawidek of FreeBSD fame used
this to manage his patches before he got commit access to FreeBSDs 
repository and he probably still uses this trick[1].

I am also interested in the easiest way to do this for the ports tree.
As of now, I have just messed up my checkout repository, but that does
indeed not seem to be intelligent. 

[1]: http://garage.freebsd.pl/developing.txt

-- 
j.