Wouldn't it be better if it was:
proc rp_handler
....
ad_call_proc_if_exists ds_add rp [list transformation [list notfound $root/$path notfound] $startclicks [clock clicks]]
set servername [ns_info server]
set config_value [ns_config "ns/server/$servername" NotFoundResponse]
if ![empty_string_p $config_value] {
rp_serve_abstract_file [acs_root_dir]/www${config_value}
return
} else {
ns_returnnotfound
}
...
That way the setting on the AOLserver config file would be respected.