This plugin allows you to use CA Harvest as a SCM.
First things first - install the plugin, either through the Hudson plugin administration, or manually. In either case, a restart of Hudson is required.
Once Hudson has restarted, select Manage Hudson from the main menu, then select Configure System from the options presented:
Once the server settings are configured, new builds can choose it for pulling down code. Create a new build, give it a job name, and select the type of build (free-style, maven2, etc) and click OK. On the subsequent screen, you'll see a section called Source Code Management where you can select Harvest. Select Harvest, and the following options will appear: