Checking whether an rc.d script was invoked from rc

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

Two probably very basic questions:

Is there a way to check whether an rc.d script was invoked from rc 
(as opposed to running it manually, via service(8) or whatever?
During autoboot, rc_fast is set, but if I go single user and back multi user 
or boot to single user and go multi user from there, it isn't.
Hovever, there is an operation (sending NAs using /usr/pkg/bin/na6) in 
a script of mine that can safely be skipped when autobooting and most probably 
during going multi user, but needs /usr mounted (I could add that to 
critical_filesystems_local, yes).

Alternatively, I could copy na6 to /local/bin (or whatever). It only needs 
libc, libpcap and libm, which are all in /lib, but ldd say the binary 
references /usr/lib. How do I change that?

Thanks.