Well, firstly, have you had a chance to explore the PROIV Control Panel? Is a Gateway setup?
The Gateway is the listener for the Task call. It has the port that would be invoked. Topic 250007 in the help has info on the various Gateway settings. I may be able to help with a few, but I'm sure there are differences between Windows and UNIX.
We also use a transparent login for our Task calls. We usually use the p4task.exe utility that comes with PROIV to invoke our Task execution or we use PROIV web services. I am unaware if there is a UNIX equivalent to the p4task, however there are some other resources available to help build an app to execute a Task.
Let me know how much of the process needs to be worked through, and I can try and be more or less detailed in a full explanation.