Selecting partions to use via preseed.cfg

[Richard Owlett <rowlett@cloud85.net>]

I am aware of the options demonstrated in 
http://www.debian.org/releases/wheezy/example-preseed.txt .

They do not cover my case of interest.
I am experimenting with various configurations of Debian.
My procedure *REQUIRES* installing Debian to a specific partition 
of of a disk already containing data and possibly other installs.

I currently handle this by deleting all partitioning information 
fro my preseed.cfg .
This forces manual intervention during which I specify which 
partition I wish to use (for / and swap).

This is the only point requiring manual intervention. I would 
like to eliminate it. The "partition recipe" approach is not 
suitable.

Ideas?
TIA