Shibboleth Developers

I would like to implement a feature in Shibboleth SP's Apache module, 
mod_shib, which will decode a custom HTTP_SHIB variable. So every time the 
module catch a HTTP_SHIB variable, it execute something like this: 
HTTP_SHIB_CUSTOMATTRIB=decode(value(HTTP_SHIB_CUSTOMATTRIB))

Is it possible?

Gabor