This has come up several times in the past few weeks, so I thought I'd better post a clarification (and it'll go permanently to the right, with the other Big Book of Socks information).
When you come upon instructions that say knit as for, referring you to a different pattern for the next step (in this case, to the 40 stitch flap and gusset heel), knit that portion of your heel as you would for the referred pattern. In other words, knit it in the same manner, using the same short-row technique as in the referenced instructions. Knitting "as for" does not mean that you are to use the same number of stitches (which would be impossible, since only the 40 stitch heel uses forty stitches). Work the first two rows of your listed heel instructions, and then continue in the same manner as the 40 stitch flap and gusset heel (in other words, work one more stitch on each row, before doing the decrease and turn), until you have worked across all of the stitches.