add formatted column to pandas data frame

[alkaline3]

Hi, I have this example:

timeList = [ '0:00:00', '0:00:15', '9:30:56' ]
totalSecs = 0
for tm in timeList:
    timeParts = [int(s) for s in tm.split(':')]
    totalSecs += (timeParts[0] * 60 + timeParts[1]) * 60 + timeParts[2]
totalSecs, sec = divmod(totalSecs, 60)
hr, min = divmod(totalSecs, 60)
print ("%d:%02d:%02d" % (hr, min, sec))

But rather than summing up the values, I'd like to add the formatted values to a new column that I can then work with. How can I do so?