With any of these ideas you might get lucky at best and get some of it to stop. Very unlikely to fix the leak. Not being able to "SEE" the other side is what kills you. You don't know what you'll be covering up by spraying or spreading any product. If you do try it you need to do your best about making sure there is no debris whatsoever in it. Best of luck with it.
cowl leak fix Its not a fix but a cure for most if not all the wter tl you take the cowl apart, If you look on ebay under maverick cowl cover magnetic you will find a vinyl coated magnetic rubber cover I make,this month I made five or six and they really help, just use as needed They are kind of time consuming to make as each one is hand cut and finished,their are two curves to match. but they will help. as far as other areas that may leak it could be windshield seal , as far as I can telleir are no other spots except wiper arm shaft area which seals up easily with siicone afteryou pop off wiper arms.
Here is a not as hard to do way if you have a mig welder http://www.stormloader.com/falconccwa/leakhint.htm
good ideas everyone, but like somebody stated earlier, these leaks are coming from the firewall to cowl bottom seam. Got to pull the fenders off and see whats going on under there.