Here's the official guide:

http://netatalk.sourceforge.net/2.0/htmldocs/configuration.html

Don't know if you've already tried using it. Just thought I'd post it for reference anyway.

You might be able to use some of this guide:

http://www.kremalicious.com/2008/06/ubuntu-as-mac-file-server-and-time-machine-volume/

There's a step where it shows the following:

ATALKD_RUN=noPAPD_RUN=no

CNID_METAD_RUN=yes

AFPD_RUN=yes

TIMELORD_RUN=no

A2BOOT_RUN=no

Click to expand...

You will want to make sure that ATALKD_RUN equals "yes" for Classic AppleTalk.

I need to setup a computer with a linux distribution and make a "Install Netatalk for Dummies" guide for people like me and others who just need something simple to follow that tells us how to setup Netatalk for Classic AppleTalk networking.

Anyway, hope these links will have something that can help you.

Edit: Oh! I just found this little gold nugget:

https://help.ubuntu.com/community/AppleTalk

That might really come in handy.