Ahhh. Thanks.Take/crop a screenshot.
Upload it to Imgur.
Paste the image's URL into your post/reply (wrapped with [img] tags).
Copy the URL for the actual tweet itself.
Highlight your image URL, click on the "Insert Link" button, and paste the URL for the actual tweet. Your posted picture is now also a posted link.
Might also want to wrap the whole thing in [quote] tags.
It should come out looking pretty, like this: