autocomplete text field with HABTM association - PLEASE HELP

can anyone help me work this functionality out? I actually have 3
classes each with a HABTM relationships with each other but right now
I am just trying to get one to work. I have 2 models, 'employees' and
'practices' (healthcare field), and would like to have a text field on
the 'employees' new and edit views so the practice(s) this employee
belongs to can be added.

I have the linking table employees_practices created successfully and
the HABTM associations created in the models (to each other).
I have installed the plugin: script/plugin install git://github.com/rails/auto_complete.git
- as it is no longer included in rails 2.3.8.
I have included the <%= javascript_include_tag :defaults %> in the
application.html.erb ((so its available throughout the app))
I have included <%= text_field_with_auto_complete :practice, :name
%> in my _form for 'employees'
I have added auto_complete_for :practice, :name to my employee
controller

i normally get some variety of 'method undefined..etc' or some other
variation no matter what i do.
couple things: I did not create a new search controller as I am
trying to add this text field to the existing views for 'employee'
generated when I used nifty_scaffold to create employee. Also I feel
like at least some of my issue is definitely in the controller, I
don't think just adding auto_complete_for :practice, :name to the
controller should work. I have tried all sorts of methods and can't
get it to work.
I would like to actually be able to list multiple 'practices' in the
field separated by commas (something about using a token?

can anyone walk me through this? help with the controller? everything
else look right?

Thanks