Modify the [IMG] button on the Write New Post page

I run WP 2.6 through Safari and have disabled the visual editor. I would like to know if it’s possible to change the [img] button so that it automatically puts in the URL to my image folder (https://www.mydomain.com/pix) instead of just the generic “https://”

It would make my linking to images much faster and easier.

Is there a way to do this?