If don't have RSLogix500 with me but this general method should work
Temp is a Sint
Temp = Sint AND xf0
Temp = Temp / 16
Temp = Temp + 48
If Temp > 57 then Temp = Temp + 7
String.Data[0] = Temp
Temp = Sint AND x0f
Temp = Temp + 48
If Temp > 57 then Temp = Temp + 7
String.Data[1] = Temp
String.Len = 2