How do I include disk driver modules in a network installer image?

[mrider]

In building debian-installer for jessie from source, I would like to 
include disk driver modules in the network installer image. How might I 
accomplish that?

I see that the installer normally loads sata-modules-3.16.0-4-amd64-di 
from the mirror, and so I tried copying that file to 
/home/user/debian-installer-20150422+deb8u1/build/localudebs/ before 
building. But that did not work. Using the resulting installer, I still 
cannot see /dev/sda in BusyBox before reaching the disk partitioning 
step.

I typically SCP installer and initrd images to a remote server, set the 
installer as default and update GRUB via SSH, and then reboot. But if 
the installer hangs during network setup, I need to get IPMI access in 
order to debug. I would rather add a script to the installer that gives 
up after an hour, writes logs to the existing system, and then reboots 
to it. But I cannot even begin to do that unless I can mount /dev/sda.