Gallery extension, changing alt-text for images?

[marc]

When I upload a image on a page or entry using the gallery extension, I can give it extra text: "Alternate text" and "Title".
I would like to change this text afterwards, is this possible?

I'm asking this because I'm combining the gallery extension with this great gallerything: http://www.twospy.com/galleriffic/
And therefore I would like to add some text to each image.