ok, i am trying to make my setup identical to yours (as in
http://cosmos.infrae.com:8080/prefs_install_products_form).

You are using Archetypes 1.3.0-rc1 (CVS/UNRELEASED) but I've
installed Archetypes 1.3.0-rc2 and now I don't get the 
AT_GENERATE_METHOD import error. And I was able to install
PloneRailroad into my Plone site.

So I suspect that there have been some changes in the most
recent AT 1.3.1 which affect PloneRailroad.

Actually, the import does not seem to be wrong - I need to
investigate a little more.

Ah, right, imported from the wrong location... Will fix that.

This might be an effect of recent refactoring of the code.
Any ideas?

I tried using the tarball releases of Railroad and
PloneRailroad (instead of the svn checkouts) and also
updated to the latest Archetypes 1.3.0-final, but I'm still
getting the error.

I issued the "grep -r AT_GENERATE_METHOD *" command in the
Products dir and discovered that AT_GENERATE_METHOD is
declared in ATRepresentations/utils.py, but
ATRepresentations is not mentioned as a dependency.

It's also imported in Archetypes/public.py:
from Products.Archetypes.ClassGen import AT_GENERATE_METHOD:

I made a new Zope instance and checked out the latest
Railroad, PloneRailroad products from svn. When I try to
start up the Zope instance, I get the following error. I'm
using Zope 2.7.2 and Plone 2.0.4.

2004-10-07T13:04:20 ERROR(200) Zope Couldn't install
PloneRailroad
Traceback (most recent call last):
  File "/usr/local/zope272/lib/python/OFS/Application.py",
line 738, in install_product
    initmethod(context)
  File
"/Users/nateaune/zopeinstances/railroad/Products/PloneRailroad/__init__.py",
line 32, in initialize
    import PloneRailroadService
  File
"/Users/nateaune/zopeinstances/railroad/Products/PloneRailroad/PloneRailroadService.py",
line 16, in ?
    class PloneRailroadService(BaseContent, service.Service):
  File
"/Users/nateaune/zopeinstances/railroad/Products/PloneRailroad/PloneRailroadService.py",
line 104, in PloneRailroadService
    client_name = AT_GENERATE_METHOD
NameError: name 'AT_GENERATE_METHOD' is not defined
Traceback (most recent call last):
  File "/usr/local/zope272/lib/python/Zope/Startup/run.py",
line 50, in ?
    run()
  File "/usr/local/zope272/lib/python/Zope/Startup/run.py",
line 19, in run
    start_zope(opts.configroot)
  File
"/usr/local/zope272/lib/python/Zope/Startup/__init__.py",
line 51, in start_zope
    starter.startZope()
  File
"/usr/local/zope272/lib/python/Zope/Startup/__init__.py",
line 230, in startZope
    Zope.startup()
  File "/usr/local/zope272/lib/python/Zope/__init__.py",
line 47, in startup
    _startup()
  File "/usr/local/zope272/lib/python/Zope/App/startup.py",
line 96, in startup
    OFS.Application.initialize(application)
  File "/usr/local/zope272/lib/python/OFS/Application.py",
line 278, in initialize
    initializer.initialize()
  File "/usr/local/zope272/lib/python/OFS/Application.py",
line 305, in initialize
    self.install_products() 
  File "/usr/local/zope272/lib/python/OFS/Application.py",
line 560, in install_products
    return install_products(app)
  File "/usr/local/zope272/lib/python/OFS/Application.py",
line 591, in install_products
    folder_permissions, raise_exc=debug_mode)
  File "/usr/local/zope272/lib/python/OFS/Application.py",
line 738, in install_product
    initmethod(context)
  File
"/Users/nateaune/zopeinstances/railroad/Products/PloneRailroad/__init__.py",
line 32, in initialize
    import PloneRailroadService
  File
"/Users/nateaune/zopeinstances/railroad/Products/PloneRailroad/PloneRailroadService.py",
line 16, in ?
    class PloneRailroadService(BaseContent, service.Service):
  File
"/Users/nateaune/zopeinstances/railroad/Products/PloneRailroad/PloneRailroadService.py",
line 104, in PloneRailroadService
    client_name = AT_GENERATE_METHOD
NameError: name 'AT_GENERATE_METHOD' is not defined