I'm having an issue with Spring.NET and Sitecore CMS, it seems like Sitecore manages the httphandlers in such a way that:
<add verb="*" path="*.aspx" type="Spring.Web.Support.PageHandlerFactory, Spring.Web"/>
Any good advice how to overcome that?
Could it eventually be intercepted through Global.asax Application_BeginRequest instead?
I'm pretty certain that Application_BeginRequest is going to be too late in the page-request lifecycle to accomplish the same thing but you can probably experiment with this by (conceptually, at least!) copying the (relevant) code out of the Spring.Web.Support.PageHandlerFactory and pasting it into your Application_BeginRequest handler to see if you can achieve the same effect that way.
A better approach would almost certainly be for you to reach out to the Sitecore CMS developers and try to determine why their CMS product is evidencing the behavior you are reporting (e.g., somehow excluding otherwise valid registrations of HTTP handlers).
Let us know if we can be of additional help here.