Saying that makes people look at you a little funny. I've learned to ignore it, but I suggest you practice shrugging when you plan a project this big, because believe me, you'll get some pretty odd looks. I personally like to keep in mind the fact that no project is too ambitious if you crave the result enough. I think there was something about that over at Mason-Dixon Knitting (link on side bar, and I strongly urdge you to take a look) a few days ago, which is probably the only reason that it's in my head.
I've got about half of an inch of my slipcover. That's a lot better than yesterday. Maybe tomorrow I'll break one inch, but don't hold your breath. I personally kind of like having this big of a project. It's like baking bread (which I did today) you just feel better for doing it. Depending on how sick of this thing by the time I'm done (probably about ready to choke myself with it.) I may even add a cushion to the cover. This ain't exactly the most comfortable chair, and could use a little padding.
But my plan of action is to simply cast on at the bottom of the chair, and knit till I get to the seat. I'll put that on a holder and wait till I'm ready for it. Then, I'll knit a strip that's as wide as the top of the back, pick up stitches all around it, and then knit till I get the to the seat. Then I'll graft the back of the back to the back of the legs (follow that?). Then I'll work on the front of the seat to the front of the back, and then graft there. The sides of the legs will be bound off, and sewn to the sides of the seat.
This would be a lot easier to understand if you could see the hand gestures that I make while I do it.