if it is the cardigan (or the back zippered) version, you can (awkwardly) knit it on straight needles
it's easier to knit on circ's (but you treat the circs as if they were straight needles!)
and 5 hours is optimistic.
i knit pretty fast, and i find i need more than 5 hours (maybe i could a premmie one in 5 hours, but not a size 6 months..)
figure it to be 10 hours (2 hours an evening, its done in a week!)
its a pretty simple design, and makes an nice baby sweater.