Slackware out of the box should be running sshd. Durring the install did you choose not to run the service? (see above)
If you did not install it-- check pkgtool-- from a root command line--
then choose view and look for "openssh", if it is not installed, download it from ftp://salckware.com
So if you know the individual IP's, then you should have no problem connecting to them from a machine within your local network.
Check to see if sshd is running on each machine. From a root command line:
ps aux | less
Look around for sshd.
If all that is ok, show us your config.