Insert HTML at cursor location

Hi! I'm a web developer and I'm trying to make it easy for my clients to insert PayPal "Add To Cart" code into a page. Since PayPal provides a code snippet as HTML, I thought it would be great if the editor had a feature that inserted a block of HTML at the current cursor location that operated similar to "Paste From Word". I looked through the available buttons and see no such action.

Any suggestions?

Thanks.

Josh