More straight forward method to convert seconds::bigint to interval

I work in VoIP.  HMS (Hour/Minute/Second) format appears to be the rule
when working with call time totals.  I admit it makes some reports
easier to read.

The method I used to convert a int/bigint to HMS (or the standard
representation of an interval type) is as follows:

select (123456.789::varchar(24) || ' seconds')::interval as HMS;
     hms
--------------
 34:17:36.789

Is there a less string oriented method of converting seconds as an int
to an interval?

- Shane