I'd like to think it's possible - it will certainly require some investigation though.
What I would try is to create a plugin that runs on OnManagerPageInit (I think), using the following to load in your custom code:
$modx->regClientStartupScript('path/to/your/code.js');
You can use a simple if condition in your plugin to only include the code when the current page action is Resource/Update. That will get your code into the Resource Update page, but getting it to display where you want is not going to be so simple.
I can't see a way to easily slot into the existing tab group. You might want to have a dig through the contents of manager/assets/modext/widgets/resource/ as that's where the core resource files for the manager are located.
Or... hope that Shaun sees this post. He can give a definite yes or no as to whether it's possible and I'm really keen to hear his suggestions