The gusset is fairly easy. It's the heel turn and grafting (without switching to 2 needles) that I'd have to do to be sure.
This is what I wrote out from memory (I find it easier to write corrections than to write out a pattern as I do it).
Cast on 44
Slip 22 to a DPN.
Alternate slipping from those 2 needles at the middle of the CO to a single needle.
Joining and ribbing
K2tog, bring yarn forward, M1 (from back CO).
* P1, keep yarn forward slip 1. K1, bring yarn forward, slip 1, P1, keep yarn forward, slip 1. Repeat from * to end of row.
Turn, * K1, bring yarn forward, slip 1, P1, keep yarn forward, slip 1. Repeat to end of row.
That is the end of round 1.
Repeat "K1, bring yarn forward, slip 1, P1, keep yarn forward, slip 1, turn" until you have your desired amount of ribbing.
*K1, bring yarn forward, slip 1. Repeat from * until desired length of leg.
Count 22 stitches and place marker.
Continue "K1, yf, sl 1" to marker. Turn, yf, sl 2 (I can't picture if this should be sl1 or sl2), *p1, sl1. Repeat from * to end of row. Turn, repeat from * to marker.
Turn, sl 1, yf, sl 1, *K1, yf, sl 1, repeat from * to end of row, turn, repeat from * to end of row.
Repeat for 22 rows.
(By now you should have the concept down so I'm going to stop telling you to slip the other side, just do it.)
(to decrease you need to rearrange your stitches so you have 2 from the side you are working on together. I do this by dropping the wayward stitch and picking it back up. But the good news is that by picking them up they're already rearranged for you on the other side, I think, if I'm wrong it will require a different type of heel turn to avoid excessive rearranging. It should work like that for the gusset.)
If you ended at a marker knit so all stitches are on one needle.
K5, K2tog, K1, turn.
Sl1 (remember I'm not telling you to slip the other side any more, just do it), P6, SSP, P1 turn.
Sl1, K7, K2tog, K1 turn.
Continue in this manner adding one more each time until you end run out of stitches, turn and knit across (or don't if that would be purling across).
Replace or leave marker on your top of foot needle. Alternate picking up stitches from each side of heel flap with your top of foot needle.
* Knit down to 3 stitches (from this side, remember I'm not referring to that side any more) before marker. K2tog, k to end, turn K to marker, K1, K2tog, knit to end.
Turn, knit one straight round.
Repeat from * until you have 44 stitches on your needles.
Knit until you have a length about 1 1/2" from the end of your toe.
Slip 22 stitches to a DPN. Alternate slipping this side and that side from the 2 needles back to your straight needle. (This is mainly to avoid using markers, I don't think it's needed.)
Knit to 3 of this side's stitches before the end. K2tog, K1. Turn, K1, SSK, knit to 3 stitches before the end, K2tog, K1, turn K1 SSK. K1 rnd even.
Repeat until 16 stitches remain.
Cut off yarn leaving a length at least 3 times wider than the sock toe.
Thread yarn onto needle.
Insert in stitch 1 as if to purl. Insert in stitch 2 as if to knit.
(I'll have to do this to get it written out accurately.)