how convert multiple selection magento in the checkbox

I have magento 1.9 and for my problem I can't find any solution. I have searched everywhere on the web but nothing. I created an attribute "product model" with 500 value inside. I set the attribute as a multiple selection but when I go to the magento backend to set the product compatible with multiple models it is very inconvenient to select many. Is it possible to convert the multiple selection of magento with a checkbox? It would be much more comfortable. I found solutions but only for the frontend, I would need it for the backend. Thank you all guys.