use firefox, right click checkbox, inspect element (q), use the info to generate an xpath, say  //input[@type="checkbox"] ie  $('input[@type="checkbox"]')  

Then check http://api.jquery.com/ for "check" and find whoa :) http://api.jquery.com/checkbox-selector/, so

 $(':checkbox').click(); clicks all of them

of if you know form name you might use $('form[@name="the name"]').filter(':checkbox').click();

Use themes for Anonymous Monk or try out themes without changing display settings to add jQuery to a page (one click) then click your check-all bookmarklet

javascript:(function(){     your code here    })()  
[download]

The original https://addons.mozilla.org/en-US/firefox/addon/web-developer/ extension has

Tools + Web Developer Extension + Forms + Toggle Checkboxes + Check All Checkboxes

Thanks, I get the DOM/jQuery/injecting script part (I'm using Opera myself and all I need to do is to put a JavaScript file in a specified userjs/ directory). It's the bit of selecting the older releases' files (and not the current releases') that I'm hoping someone has already written.

Anyway, I'm hacking on it... Will be posting to my blog when it's done.

that I'm hoping someone has already written.

I've not used my PAUSE account in about 9 years, I don't know what the HTML looks like, but I do know javascript regex are a lot like perl, http://interglacial.com/~sburke/pub/JavaScript/JavaScript_equivalents_of_Perl_regexps.html

The might be some modules that already do what you want, e.g App::PAUSE::cleanup or WWW::PAUSE::CleanUpHomeDir.

D'oh, that's the one thing I forgot. WWW::PAUSE::CleanUpHomeDir comes closest to what I need, with its cleanup() method. But anyway, in case anyone needs it, I've also written the JavaScript (tested in Opera). At least, using the browser + JavaScript you can double check visually before hitting Delete.

https://github.com/sharyanto/userjs/blob/master/pause-delete_files-select_all_older_releases_files.user.js

Thanks everybody.