Int 2F Fn BF80  - PC LAN Prog Redir.sys Internal - Set Redirifs Entry Poi  [N]

   AX = BF80h
   ES:DI -> FAR entry point to IFS handler in REDIRIFS

Return: AL = FFh if installed
       ES:DI -> internal workspace

Note:  all future IFS calls to REDIR.SYS are passed to the ES:DI entry point