[Zope] Writing custom tags "through the web"

[Gerald Gutierrez]

I've found custom tags invaluable in my daily J2EE use, and would like to 
do the same with Zope. I'd like to be able to do it like everything else I 
do with zope, through the web browser interface.

Unfortunately, the only documents I've found relating to custom tags tell 
me that I must modify the Zope source code and write these tags as 
filesystem products or classes.

Is there no way to write custom tags through the web in Zope?