Uploading presets is now possible using File Attachment under the Options tab when posting. File types allowed are limited to:
zip;cab;jpg;gif;png;mpg;mpeg;avi;wmv;wma;mp3;ra;rar;rm;sql;txt
which means you should zip up .syx files before trying to post.
For information about saving your presets to a computer, visit the FAQ pages:
http://forum.eventide.com/cs/forums/t/5010.aspx
http://forum.eventide.com/cs/forums/t/5011.aspx
Also, PC users can refer to the video tutorial by Roobin12:
http://www.youtube.com/watch?v=6Q1sEVca2_E