Add the gems to you Gemfile:
gem 'delayed_job', '2.1.0.pre2' gem 'delayed_job_data_mapper', '1.0.0.rc'
Add this in an initializer:
# config/initializers/delayed_job.rb
Delayed::Worker.backend.auto_upgrade!
That's it. Use delayed_job as normal.
$> rake build
>>> Building historian_djdm-1.0.1.gem ...
$> rake release
>>> Tagging v1.0.1 ...
$> cat ~/.gem/credentials
---
:rubygems_api_key: XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
:historian_api_key: YYYYYYYYYYYYYYYYYYYYYYYYYYY
$> gem push -k historian_api_key pkg/historian_djdm-1.0.1.gem