The only way know you add php code is to add it to the php source code, you can put special iframe and other html but to put php you need to mod the script to parse it properly. What you are wanting to do is not an option.
To better explain this, i have a members map that is a wordpress plugin that i use on my wordpress blog. I could not include that php to show the map on my oxwall page, but once the page was parsed and rendered i could include the iframe to the page. So i made a members map page on oxwall and used the iframe and now my members map shows in my oxwall page.
Does that help.