X-Cart forums - changing buttons

Anyone help me out with this little problem? i know it must be something simple but im just missing it, in my checkout (jons ezcheckout) I have the buttons at the bottom , which are taken from text variables, i want to change them to gifs instead to make them look nice and more obvious, problem is if i just change the button.tpl for them i seem to lose functionality.

at the moment the code where the buttons are on the page looks like this

Code:

<TABLE border="0" cellpadding="0" cellspacing="0" width="100%"> 



<TR> 



<TD> 



{include file="buttons/update.tpl" type="input" href="javascript: document.cartform.submit()" js_to_href="Y"} 



 



{include file="buttons/button.tpl" button_title=$lng.lbl_clear_cart href="cart.php?mode=clear_cart"} 



</TD> 



<TD>{include file="buttons/continue_shopping.tpl" goto="product"}</TD>

<TD align="right"> 



{include file="buttons/button.tpl" button_title=$lng.lbl_checkout style="button"  href="cart.php?mode=checkout"} 



</TD> 



</TR> 



</TABLE>

i've got my images ready, so i just need to insert them so that they retain the same functionality but not sure what to do.