Request this hotpatch from Novell:

ZDM7 SP1 Hot Patch (ZENworks 7 Desktop Management SP1 Hot Patch 2)

It contains an updated bootcd.iso that will work with the GX745

The following was posted in a previous thread:

The imaging path is located in a compiled file called IMG, which is
located inside the LINUX3.TAR file, which is inside the LINUX3.TGZ on the
Zen imaging boot CD. IMG can be opened with a hex editor, then
the /path/images/ string can be replaced with a string of your choice.
Here are the steps I used:
Full Article:
http://forums.novell.com/group/novell.support.zenworks.desktop-management.6x.imaging/message.../@article@4778

These files do not appear to exist in version 7.0.1.2 and instead there
appears to be a file called initrd. Extracting the contents of this file
does not reveal any reference to an img file. This may not be supported
but I sure would like to be able to modify the /path/archive.zmg from the
default. Anyone have new info on how to do this?

Thanks
Joe

Having problems with imaging our HP DC700 computers with Zen Sp1. If I use
PXE boot (2.6.5-7.244) I get a "no network device found" message. I guess
to drivers not being available.

I have tried using the 2.6.18.3 from zenimaging.info but this display a
blank screen and hangs after selecting automatic or manual from the menu.

I'm not up to speed with some of the more advance methods of creating new
Zen boot disks? Is there an easy way to add the required drivers to the
PXE files on the server or does someone have an ISO created which would do
this?

Regards Derek