Although it did take quite long, finally a russion guy has implemented a hack for the 300D to get the features of the Canon 10D!
“The 10D has a menu item called “Custom Functions” which allows these settings to be adjusted. Well, a fellow in Russia found that in the latest firmware, by switching a single byte in the firmware image, he was able to enable most of these 10D ‘Custom Functions’ in the Digital Rebel. Now, some features, such as more frames in rapid shooting, are hardware-limitations but some features lacking such as Flash Exposure Compensation and embedded JPEG quality are found to be working in the 300D”
Find out all yourselves at the Digital Rebel Tricks page. Find out yourselves, it saves you about $500,-