As per Ian Bicking's
suggestion in the Web-SIG mailing list, ajp and scgi will now use the environment variable WSGI_SCRIPT_NAME (as passed from the web server) as the scriptName. Note that at this time, cgi2scgi and mod_scgi do not pass extra environment variables. (mod_jk can pass extra variables via the JkEnvVar directive.)
Currently, WSGI_SCRIPT_NAME overrides scriptName. If anyone sees a problem with this, say so now.
Also, scgi will accept a scriptName of None. In this case, scgi will not touch the environment at all. (It is assumed to be correct as is the case when using cgi2scgi.)