Why doesn't Tor support 4a?

[ADB <firefox-gen@xxxxxxxxxx>]

Dear Roger,
   Why does Tor support SOCKS 4 and 5 protocols but not 4a? Getting 
this implemented would surely eliminate the security risks and user-end 
headaches associated with using other applications to get around this 
problem.
   Alternatively, if there's some reason why this has to be the case, 
has anyone thought of doing one of the following as a work-around?

A. Setting tor-resolv as the system's default name-server via some 
registry (win32), shell (unix) or stack-level hack?
B. Configuring BIND/named via it's own config files and/or iptables to 
resolve DNS names via tor on port 9050. If named is caching names in a 
secure way, you could speed resolving up a bit too perhaps.
C. If I'm wrong about all this, please feel free to just slap my ass and 
call me 'Sally' :D

~Andrew