Oh my those are so cute!
Oops...sorry about the instructions. I haven't updated the pattern, but basically here is how you do it. When you have completed #4 and have 50 stitches:
Continue to increase every other row by increasing in the first and last of the knit stitches. That keeps the increases nice and neat and the pumpkin ribs aren't interrupted. Then knit straight as per #5, but you will need to do more than 4 inches. How much more you do is dependent on how many increases you did and how you want your pumpkin shaped. Less would give you a wider squattier pumpkin, more would be taller and more round. NOTE: you may need to use a longer needle for bringing the tail from the bottom to the top and be very careful not to lose the needle in the pumpkin.
Does this make sense to you?