Default 'timestamp' value on HP-UX running Postgresql6.3.2

I am running postgres 6.3.2 on HP_UX 10.2. I have a field defined as
type 'timestamp' and am using ISO datestyle. The default value shows
up as the string constant 'epoch'. Is there any way of having the numeric
value of '1970-01-01 00:00:00+00'  returned instead??

I appreciate any help! Thanks.
-sr