if you want to be clever and do something not "officially" supported by Oracle you could save a load testing scenario in e-Load and then record a simple e-Tester script that called e-Load, opened the saved scenario and then pressed the "play" button. You could choose to leave the e-Load UI open or you could detach from the scenario and close the window. You would have to make sure that you were auto-saving and auto-naming reporting sessions. You could then put your e-Tester scrip in job scheduler and schedule the test to begin. I done this several times and it works pretty good
Give it a try and see if it meets your need.