Hi, just change the button display link in the corresponding template file.
The template is called "block_basket.html" and is in the "/templates/user" folder.
Search for <!-- end coupon_form --> and change the links below to your liking. Remove the "class" and add a graphic. An example of how we changed our product buttons to be graphics:
<!-- begin add_button -->
<a id="add" href="{buy_href}" onClick="return confirmBuy(document.form_{item_id});"><img src="images/ico-buynow.gif" alt="{ADD_TO_CART_MSG}" border="0" align="absmiddle"></a>
<!-- end add_button -->
Hope this helps and is what you are looking for. If not, pls clarify.
DickS
