and... I seem to be solving my own problem, so I'll share.
Ninanet's code is great.
I dropped the php part into the <head> area of the default theme's index.php file.
Further down I found the "gallery description" insert point, deleted that line, and replaced it with the HTML from nina's code.
Took a bit of tweaking (I removed the text so that only the twitter content shows, reformatted it a bit) but it works.
post here if you'd like more description though I'm sure most of you know far more than me.
Thanks!