Geoff, as far as I know, water injection died out as a means of thrust augmentation in the seventies, once high by-pass turbofans came on the scene with their ample thust reserves for take-off. It was a good idea at the time though, when they only had turbojets and low BP turbofans.
Nomally the water was injected upstream of the compressor, which vaporizes causing temperature to drop, in turn causing density, hence mass to increase, providing the extra thrust due to increased mass flow rate.
According to theory, thrust depends on airstream velocity and mass flow rate, which is linked to air density (mass=density x volume). Density increases with pressure and decreases with temperature, so the water injection helped at high altitude airports, and on hot days.
Not sure about the methanol mix though,whether it was injected direct into the combustors or not.
Here's a rough way to start up on a hot day. It's an An-24 turbo-prop. Fairly sure it's at Chita, just north of the Mongolian border in Eastern Russia.
Cheers, Willie.