SOS on code snippet on specific location

Hi everyone, I am new in WordPress and I am desperate for one thing which caused me troubles for a month…….

I want to add a block of code snippet into a Specific Location of a Specific page of my web.I know how to modify the theme and most plugins are used to modify the theme. That code snippet could be written in Javascript, PHP, Ruby….(It is used for web analytics tool called KissMetrics for advanced features, also please don’y tell me plugins like Kissherder cuz it is only used to activate the most basic tracking purpose, advanced purpose like tracking a form submission must be accomplished by inserting a code snippet into a specific position of a specific page’s code).

Thank you guys! That’s so important for me!!!!!!