have a generic button that will automatically issues a SITE command but allow a user to type in the command. for example:
hit the button and you are presented w/ a dialog box that has the word SITE all ready entered and allows you to enter whatever you want. Like SITE SEARCH xxx or the like. BPFTP has this option.
This is already possible. Make a custom command linked to a key (rather than a button, we've limited space..) that will prompt you for information and use it in the command.