I've done the water injection cleaning in nearly all my family's cars (past and present, with the exception of the '91, for obvious reasons of the turbo).

My method -

Start with the engine off. :) I don't want to hear anyone complaining that they just got their hands caught in the fan or something stupid ...

If cruise control is present, disconnect that hose off the intake manifold. If not, find something else "unnecessary" for the meantime. Use that inlet for the water hose, which I use the clear aquarium air hoses. With a zip tie, hold it in place on the nipple.

Route the hose around to the interior. It's fine to run it outside, as the hose is temporary. The other end goes to a 1-gallon bottle of distilled water. The bottle has to be secure ... you don't want it to tip over.

Start the car, and see if there's sufficient vacuum to suck the water through the hose - if not, there's something else causing low vacuum ... that's up to you to diagnose.

If so, that's good. But don't start feeding all the water yet ... this is only effective when the engine is running high and hot. So get on the highway, then put the tube in. It should now suck at a continous stream. Keep the revs above 3k ... it'll be more effective. If you have to drop down below 1500, stop the water. It'll feed too much and could cause stalling.

Everything should now be fine and dandy when the water's gone. If it was bad, you'd feel a big difference (more power!) on your way back.

-- Kane ... who's not responsible for your (mis)actions, so I'm disclaiming to do this at your own risk.