Just as a quick note (this is my last week of midterms

: you should be able (as you indicated) to use the
php_value upload_max_filesize 20M line to configure this setting in your .htaccess file. If this doesn't work it is most likely due to a server configuration. In CompactCMS there is no restriction on file sizes anywhere in the project (it's not CCMS to manage).
I recon that the extensiveness of the .htaccess file could cause trouble here. You could try (as a test) to just add this in your .htaccess (all other removed)
Options +FollowSymLinks
RewriteEngine On
RewriteBase /
RewriteRule ^([^/]+)\.html$ index.php?page=$1 [L]
RewriteRule ^print/([^/]+)\.html$ afdrukken.php?page=$1 [L]
RewriteRule ^admin/includes/js/(.+\.js)$ admin/includes/combine.inc.php?type=javascript&files=$1 [L]
RewriteRule ^admin/img/styles/(.+\.css)$ admin/includes/combine.inc.php?type=css&files=$1 [L]
RewriteRule ^sitemap\.xml$ lib/sitemap.php [L]
php_value upload_max_filesize 20M
If that does work, then it's due to the .htaccess file of CCMS. Otherwise it's a server setting that needs changing. Check whether you have access to your own personal php.ini file (that overrides the server default) or consult your hosting provider.
Let me know!
Xander.
P.s.: I'll be finished Friday, then will enjoy the weekend to relax and will try to fill contents again for Wiki and other pages, after which I'd like to work towards releasing
CCMS 1.3.3.