The Samba schema files are included with the source. You can access them online through websvn at:
this location. The file you are looking for, and likely the only one that you will need, is the
samba.schema file. Save that as samba.schema, put it in your schema directory, and add an include statement for it in slapd.conf. Unfortunately, the locations of those vary from distribution to distribution, so I can't be much more help than that.
