Panini does list a checklist for the insert set. Card numbers from their checklist are obviously wrong though. http://www.paniniamerica.net/dspFullChecklistbyID.cfm?prod=290 According to CC, it's a 40 card set with different cards from the 1990-91 Score brands.
Here is the print run for each style of card from CC. "1990-91 Score US (blue Score logo on front) limited to 20 copies or less. 1990-91 Score Rookie & Traded limited to 15 copies or less (Yellow border).1990-91 Score Billingual (red logo) limited to five copies or less."