Create a custom function in adhoc editor

Hi,

I am using commertial AWS Jasperserver 6.1.0 hourly, with domain and adhoc creation using domain. I am having duration fields in my domain which are populated with seconds value (integer type). I want to format the duration fields as HH:MM:SS format rather than showing them as numbers. I can convert the number to HH:MM:SS from sql however it does not support Summary total calculation, so want to know how I can write custom function to implement the same in 6.1.0 version.

Regards,

Sandeep