Jigoshop

Hi,
I know this isn't one of your plug-ins but I thought you might be able to help me anyway. I want to change the text "out of stock" & "in stock" to "call for details" & "available"

The folks over at Jigoshop suggested I use http://wordpress.org/extend/plugins/codestyling-localization
However this seems like overkill to me to have to install this huge plug-in just to change a little text and I don't understand how to accomplish it with that tool either.

Thank you for your help.

Cyndie