How to use a local Debian mirror when installing with preseed (PXE)?

[Frank Thommen <f.thommen@dkfz-heidelberg.de>]

Hi,

I'm currently setting up an unattended, PXE-based network installation 
of Debian with preseeding.  We also have a complete local Debian mirror 
for inhouse use.  However I haven't found a way to configure the 
installer to use this mirror instead of one of the official Debian 
mirrors (and takes accordingly long) for downloading the packages.  I 
have set

d-i apt-setup/local0/repository string  http://our.debmirror stable main

in the preseed file but the installer doesn't seem to download any files 
from there a part from some index files (Packages.xz, Translation-en.bz2 
ecc.)

How can I preseed our local mirror as primary/only installation source?

Cheers
frank

--
Frank Thommen           | HD-HuB / DKFZ Heidelberg
                        | System Administrator
                        | f.thommen@dkfz-heidelberg.de