[Exim] Maildir and user .forward files

I am trying to use Exim's .forward/filtering system to redirect
mailing list messages into different folders. The .forward files seem
to work as long as the messages are delivered to a single file.
However, I am using Maildir. This is my .forward config:

userforward:
driver = forwardfile
file_transport = address_file
pipe_transport = address_pipe
reply_transport = address_reply
no_verify
check_ancestor
file = .forward
modemask = 002
filter

And my testing .forward:

# Exim filter
if $h_From: contains "test@???" then
save /home/user/Maildir/.Test/
endif

And the results:

2002-11-05 13:03:34 189834-0003o4-00 == /home/user/Maildir/.MDaemon/ <local@???> D=userforward defer (-31): directory_transport unset in userforward driver

Now I checked the FAQs for the directory_transport, I'm confused on how to set this up so it is generic per user. I have the following as my transport:

maildir_delivery:
driver = appendfile
directory = /home/$local_part/Maildir
delivery_date_add
envelope_to_add
return_path_add
maildir_format
prefix =
suffix =
check_string =

I apologize, this is really getting long :) I am assuming I have to create another transport, but what do I set the directory = to so it can grab that required info from the users .forward file?