Hy,
I found out about this command, really great for modifiying files in /etc/rc.config.d/ in scripts.
NAME
ch_rc - change system configuration file
SYNOPSIS
/usr/sbin/ch_rc -a|-r|-l [-v] [-A] [-R root] [-p
{parameter|parameter=value}...] [file...]
DESCRIPTION
ch_rc manages the addition, modification, removal, and retrieval of
information stored in files having the format of those in the
/etc/rc.config.d directory.
Parameter names are treated as strings. Thus, X[0] has no special
meaning to ch_rc in relation to other parameters named X[1] or X.
you want to enable nfs_server for example:
/usr/sbin/ch_rc -a -p NFS_SERVER=1
and you are done!.