<p>I was wondering if there is a good way to hook into the Application_Start of a SharePoint 2007 site when developing a feature? I know I can directly edit the Global.asax file in the site root, but is there a way to do this so that it gets deployed with the feature?</p>

<p>Thanks!</p>

My gut feeling on this is that it won't be possible. Application_Start is called by the runtime as the asp.net engine is starting up, so there most likely can't be any way to hook the handler outside of modifying the Global.asax - e.g. the hook must be declarative and persistent as it has to survive the application stopping/unloading. So, if you have to write to the global.asax, I guess you could write a Feature EventReceiver to perform the modification.
That aside, can you give more details on the why? Perhaps there are other angles of attack. The idea of modifying the global.asax on the fly makes me feel ill. That can't be good.
Oisin