Those instructions do actually work on 2000 models as well. I have a 2000 model myself and everything worked fine by following everything in that tutorial.
If you noticed, there's actually a little paragraph that explains how to temporarily never shutdown after 5 minutes:
- Turn off your Vita completely
- Connect the powercable -> the vita should start into DemoMode
- Deactivate the DemoMode by pressing and holding L + R + UP + START for 5 seconds
- Press the Power Button to standby your Vita and wait till the blue led is completely off
- Disconnect the cable and wake up your Vita
I don't believe there are any other workarounds for preventing shutdown without having to do this method, but some developer may look into it once we have
full access to the system.