txt=Get Clipboard();
New Window( "Example", sb = Script Box( txt ) );
with a toolbar

Thanks!
How do I... Make a Custom Toolbar Shortcut? Can I do it with a cat? Yes!
Using JMP > Customize Menus and Toolbars > Customize JMP Toolbars and Menus on Windows
Using JMP > Customize Menus and Toolbars > Customize JMP Toolbars and Menus on Windows > Create Menu Items and Toolbar Buttons
Also I would suggest using script type new window if possible
Names Default To Here(1);
script = Get Clipboard();
ex = New Window("Script example", <<TYPE></TYPE>
and if you wish to have the text in current script editor, I have to ask, why wouldn't you just paste it there? This can help with scripting the script editor if needed Scripting Guide > Display Trees > Scripting the Script Editor