Starting a process from a web URL.

I couldn't find a way to have a task initiate a workflow process.

What I did was just had a publish event integration service that publishes an empty document to start the process. Then you can just have a web link to the invoke step like 

 http://<server>:5555/invoke/DtMigrationChecklist.v1.flow:publishRequestMigrationEvent 

Then my first step of the process was the task for filling in the data.  This indirectly starts the process "from a task".  We used it for our migration process for getting code from development up to QA and then tested and approved.