How To Do Live Element Editing

I am making an application that gives the user the ability to change the appearance and characteristics of a website locally. I am fully aware of how normally you can set values through ID's and Name's, but in this case the value I intend to change has neither of these things. Here is the code I want to edit:

<!--/** * Inferno Shoutbox Javascript Engine * Created By Inferno Technologies * All Rights Reserved * * * * * * * * * * * * * * * */InfernoShoutbox = new _ishout;InfernoShoutbox.aop = true;InfernoShoutbox.initiate('index','600','1','0','0','0','3','200',parseInt("5") * 1000);InfernoShoutbox.idle = true;-->

The part of the code I want to change is the '1000' which is in bold and underlined. I want to change it to 999999999 on the click of a button.