Passing parameters to PHP in templates

Hi I am currently trying to break up a huge php script into a series of templates so that they can be accessed quickly, but am trying to figure out how I can pass values to them using something other than URL segments. Usually with PHP you can just call the script and pass in extra parameters which are seen as request headers, e.g. filename.php?task=a&subtask=b&subsubtask=c

Is there a way to do this when calling ee templates? I need these templates to be called by ajax posts and gets, if anyone is interested in the reasoning behind this.

[Mod Edit: Moved to the Development and Programming forum]