How do I input WR/TE and WR/RB flex options into Full Impact Draft Simulator?

For your starting roster requirements of QB, RB, RB, WR, WR, TE, WR/TE, WR/RB, K, DEF, try: 1-QB, 2.5-RB, 3-WR, 1.5-TE etc... The simulator allows for fractional averages.