Accessing checkboxes with faces when using Facebook "send" button

I've messed around with FBML (deprecated, I know) and the newer HTML5 code to no end, but so far I haven't found any way to do what I'm looking to do.

When using "apprequest" within an application on Facebook (within iframe), I can allow users to share requests to join the app, but those messages that get sent are very hidden away. They don't seem to appear in the newsfeed for s开发者_运维百科hared recipients, and we're afraid users won't see the request from their friends.

Instead, we thought we'd allow users to alternatively share to their friends with the "send" button code that Facebook offers up. This allows us to specify a URL (we were thinking the app canvas URL or page tab it would live on).

So far, this is all I could generate...

Is there any way to have the send code let me specify that we want faces with checkboxes for uses to select their friends, instead of a sharing party needing to type out names of their friends by hand? There's got to be some easy way of doing this.

Stop me if you think I'm going in the wrong direction on this. Maybe there's a better way that I'm simply not thinking of.

Here's an example of the checkbox functionality I'm referring to...

This violates the browser security model and also Facebook's policies, you can include a to parameter with the send dialog to preselect one recipient, but you can't modify the browser DOM because the Facebook dialog is in an iframe