substituting proxy

[Robin Becker]

Before attempting to reinvent the wheel has anyone created an http(s) proxy that 
can replace the content for specific requests.

Context: I have access to the client's test site, but a lot of the  requests are 
dynamic and save html complete etc etc doesn't work properly. In addition lots 
of the content comes from a cloud server which seems to object unless I take 
great care over spoofing of host names & referrers etc.

I would like to debug stuff we supply, but that's hard unless I have the whole 
kit & kaboodle. I thought a proxy that could substitute for our javascript 
file(s) might work.

Has anyone done this in twisted pymiproxy etc etc?
-- 
Robin Becker