custom htaccess rules for photoblog

Hi all,
I wrote a custom photo album for my blog (I’m thinking to release it as a plugin for WP, but I must complete the admin section).
Now I want to rewrite the URIs for the photo album, in this way

mysite.it/pics/?album=album1 should be: mysite.it/pics/album1/

and

mysite.it/pics/?album=album1&photo=photo1 should be: mysite.it/pics/album1/photo1/

pics is a normal WP 1.5 page created using a custom template in which I call some PHP functions for the photoblog.
Now I don’t know exactly what rules I can use to do this… I already have an .htaccess file working for my permalinks structure:

/%year%/%postname%.html

Can you help me to define the correct mod_rewrite rules?
Thanks!