the startup script is in /etc/rc.d/rc.samba. your following a non slack specific guide it would seem. Read the thread I started on this same page about "rc.samba useless?". It helped me alot. Depending on your needs, you may not even need to run the samba script.
The Samba wiki here on LQ was all I needed to read in order to get Slack talking to Xp.... Switching directions would seem to be slightly more complicated. I'm not sure how much more complicated. Thats my next project apparently.