I don't think it is possible to lock a program or hide it from the taskmanager. You can run it as a service to hide it from the taskmanager but that's a whole different case. The only softwares I could find (to hide from taskbar) was this:
Taskbar Hide - Free software downloads and software reviews - CNET Downloads
Hide programs from taskbar, screen and tray with Hide Window Plus
Instantly hide programs, lock computer Hide applications windows quickly by Hotkey.