ActionWebService in Rails 2.0


I tried upgrading my application from 1.2.6 to 2.0.1. One thing that
doesn’t work is ActionWebService.
As stated in this blog:

I did a
gem install actionwebservice

But I’m not able to load it, because the latest gem version is 1.2.6 and
when requiring, it raises:
/usr/local/lib/site_ruby/1.8/rubygems.rb:246:in `activate’: can’t
activate actionpack (= 1.13.6), already activated actionpack-2.0.1]

How to get it running?