Upload huge files to a server

I have a webpage where I want my users to upload their own files. Usually these files are up to 3Gigabytes large and I can't use htaccess to increase the upload size...

The problem is, I have absolutely no idea how to manage this... I've read some similar questions on SO and they're quite confusing.

I've already tried a JavaScript 'extension' called ftp.apixml.net and it's not working

So all I want is to upload a huge file to a ftp server.

Any ideas how to do so are very appreciated. Thanks in advance! :)