Flat rate shipping module

I am using 3 different flat rate shipping options and would like to add some more text to these on the shipping checkout page. I don't want to add the text to "module_shipping_flat_text_title" or "module_shipping_flat_text_way" as this will add it onto the invoice etc.

Presently I have:

Australia Post Economy (NOT registered)
2-7 business day delivery

and I want:

Australia Post Economy (NOT registered)
2-7 business day delivery
This service is not registered therefore the customer accepts all risk if the parcel is lost
in transit.

Please note that:
module_shipping_flat_text_title = "Australia Post Economy (NOT registered) and"
module_shipping_flat_text_way = "2-7 business day delivery"

Any help would be appreciated - even just pointing me to the right file.