Yes, it's done by editing the httpd.conf file (turn on AllowOverride all) and creating a .htaccess file in your root web directory.
Here is a sample .htaccess file
Options -Multiviews
RewriteEngine On
RewriteBase /
RewriteRule ^l/(.*)$ /somescript.php?key=$1 [L]
The above will direct
https://www.dropbox.com/l/I2QT40oSwU0AoH7g02cAHI
to
https://www.dropbox.com/somescript.php?key=I2QT40oSwU0AoH7g02cAHI