I found it! Here's the formula (from crystal's knowledge base...was buried in another function):
local numbervar RemainingSeconds;
local numbervar Hours ;
local numbervar Minutes;
local numbervar Seconds;
//divide the @TotalSeconds by 3600 to calculate hours. Use truncate to remove the decimal portion.
Hours := truncate({Agent_Skill_Group_Half_Hour.TalkInTimeToHalf} / 3600);
//
RemainingSeconds := {Agent_Skill_Group_Half_Hour.TalkInTimeToHalf} - (Hours * 3600);//subtract the hours portion to get //RemainingSeconds
//Divide RemainingSeconds by 60 to get minutes. Use truncate to remove the decimal portion.
Minutes := truncate(RemainingSeconds/60);
//subtract the Hours and Minutes and what is left over is seconds.
Seconds := {Agent_Skill_Group_Half_Hour.TalkInTimeToHalf} - (Hours * 3600) - (Minutes * 60);
//format the hours, minutes, and seconds to hh:mm:ss
totext(Hours,"00"

+ ":" + totext(Minutes,"00"

+ ":" + totext(Seconds,"00"
