Wire one of these
http://nealmoser.com/store/index.php?main_page=product_info&cPath=5&products_id=121&zenid=456cfe45c2a219659a41a9a20e3bd36d
to a push/push pot & you're good to go.
Best thing is, if the battery dies, you can still play with the boost turned to the off position, it won't leave you silent.