I have done the nasty salt thing and it really does make me gag- however I think the idea of drinking the salt and then the water might throw off the water/salt balance. There are lots of reasons for the amounts (I have read too much on the subject and can't say exactly why I it is bad, but...)- it is supposed to be the same salt/water balance as your body. The amount of salt to water is to make it pass through the body so you don't digest the salt (it is A LOT of salt) or the water- hence, the 'shower' effect- this is where I think a shot of saltwater would not sit too well before the water 'met up' with it- or however it works.
**but by all means, if you try it and it works-- I will thank you a thousand times and then do it your way from now on** It really is putrid