Customizing tag inserting

I try to set up my coding enviroment, and one question not answered by either
help nor forum is the following:

I try to customize my tag inserting:

when i type : "<im" then dw automaticly realizes that i want to insert an
image-tag;
when i press enter dw extends the typed 'till the tag is finished;
but what i want is that dw should automaticly insert
a blank ' alt="" ' attribute and close the tag with a ">";
like you can customize HTML-Kit code inserting...

I tried to look for something useful in the tag library but i just found case
adjustment, etc..

thx in advance,

Kjell