Default values for custom fields after opening form

Hello everybody,

is there any possibility to set default values for some custom fields
right after opening form, not after pressing create button. I found just
the way of setting default values after pressing create button (you can
find it here http://wiki.bestpractical.com/view/DefaultCustomFieldValue).

I am using Request Tracker 3.8.1.

Tahnks in advance for any help,
Tom.