These comics were available two ways:
1) Inside selected Marvel comics cover-dated June, July, August and September 1999.
2) As a set of four via mail order for two UPC codes from six-packs of Kidz Water, or one UPC code from a 12-pack of Kidz Water (plus 1.99 USD for postage & handling).
These comics were inserted into Marvel comics in between the two 16-page signatures. They were just folded in; they were not stapled into the larger comic and could be easily removed.