Yes, the monogrammer will work on any of the Slant-O-Matics except the 404 and any of the 500, 600 and 700 series of Slant-O-Matics and Touch & Sews, with the exception of one or two early T&S's which were straight-stitch only machines.
The Deluxe Monogrammer was furnished with a flower design bar and a certificate for three "free" letter design bars. The individual letter design bars were sold as options in Singer stores and by mail order.
I was lucky enough to buy a 500 in a desk cabinet that had the Deluxe Monogrammer with all 26 letters, along with every other type of attachment available in the 1960's-70's.
There was a different monogrammer set that made smaller letters, and round design disks for each letter were provided either with the monogrammer or as a separate set, so you could buy the monogrammer and/or the set of letters. That monogrammer was made for slant and low shank models, but I don't believe either type ever worked with straight-stitch only machines.
There are manuals available for the monogrammer on eBay:
http://www.ebay.com/itm/270889405121
http://www.ebay.com/itm/140645895482 Buy It Now$14.95