Magic Fields alt tag for get_image function

Hi,

I was wondering if someone could tell me how to get a dynamic alt tag with the get_image function in Magic Fields.

I really need to use custom params (height and width) so gen_image is not an option… as far as i’m aware you cant use the gen_image function and still use custom params? If i am wrong please correct me and show me how.

Cheers
colt5034