Kakuna and Whismur aren't in the same egg group. Conveniently enough, however, Snover and Whismur ARE in the same egg group. So keep that 0 IV until the end.
Step 0.5) Make sure Kakuna is Male.
Step 1) Transfer the 4 IVs from a Male Kakuna holding the Destiny Knot to a Female Paras or Parasect until the offspring has the 4 IVs you want and is male.
Step 2) Breed that Male Paras holding a Destiny Knot with your 4 IVs with a Female from the Chikorita line, Tropius, or the Turtwig Line until the offspring has the 4 IVs you want.
Step 3) Breed that new 4 IV offspring holding a Destiny Knot with your Whismur holding a Power Anklet, to transfer the Speed IV and the 4 IVs.
Step 4) Breed that new offspring with the 4 31 IVs and the 0 IV in Speed with a Female Snover or Abomonasnow.