getty replacement

Hi guys.

Is there any way to replace "/usr/libexec/getty Pc"  with a custom application and what would be requirements for such an app?
Running 
ttyv0 "/some/app/shell_code.sh Pc" cons23 on secure 
gives me:
init: getty repeating too quickly on port /dev/ttyv0, sleeping 30 secs
and my code is not executed.