rcpar is still experimental.

rcpar starts programs in parallel, specially useful to start initscripts.

To use rcpar you'll need to modify /etc/init.d/rc:
modify the CONCURRENCY variable:
CONCURRENCY=rcpar

and add rcpar to the case "$CONCURRENCY"
  rcpar)
	startup() {
		action=$1
		shift
		scripts="$@"
		sh=sh
		
		# Debian Policy §9.3.1 requires .sh scripts in runlevel S to be sourced
		# However, some important packages currently contain .sh scripts
		# that do "exit" at some point, thus killing this process.  Bad!
		#[ S = "$runlevel" ] && sh=.
		# Make sure .sh scripts are sourced in runlevel S
		if [ "S" = "$runlevel" ] ; then
			newscripts=
			for script in $scripts ; do
				case "$script" in
				  *.sh)
					# set "$action"
					# RC_SAVE_PATH="$PATH"
					$debug $sh "$script" $action
					# PATH="$RC_SAVE_PATH"
					;;
				  *)
					newscripts="$newscripts $script"
					;;
				esac
			done
			scripts="$newscripts"
		fi

		# rcpar *experimental*
		[ -n "$scripts" ] && $debug rcpar -a $action $scripts
	}
	;;

add the -v parameter if you miss the normal scripts' output.

rcpar does not handle interactive programs, yet.