Hedblom shot an 8-under 67 and Millar had a 69 to total 8-under 136 at Aloha Golf Club.
Robert Dinwiddie of England (65), Thomas Levet of France (68) and David Lynn of England (67) were tied for third at 137. Defending champion Lee Westwood (73) was one of seven golfers another shot back at 138.
Two-time Masters champion Jose Maria Olazabal (72) made the cut on his return to the sport after a nine-month absence because of back problems.
I played 18 holes for the first three days I was here'Tuesday, Wednesday and Thursday'and I have to admit I did feel it a little bit in my lower back, Olazabal said. My game is a little below par and I think that only three birdies in two days around here tells its own story. But I have made the cut.
Olazabals last previous competitive appearance was at the PGA Championship in August.