It is enabled by default. You should see an error in the log if something failed here.
I tried to post this several times already, but for some reason I can't submit to this site from work anymore.
I tested this by creating a SQL Agent job that does nothing except WAITFOR DELAY for one minute.
I created a VisualCron job with a SQL task set to run that job.
When I run the job in VisualCron, it returns (reporting success) almost immediately. On SQL Server, I can see that the job continues running for the full minute.
This is consistent with the behavior I'm seeing from the SQL Job task that was the main reason I was looking forward to this feature.
We are still on 6.1.7. We do plan on upgrading to 6.1.8 soon.