It can be done. I canīt remember just how, but i have made it possible sometime ago. I remember i did through one of the howtos at
http://www.tldp.org . First of all you need a hibernate partition, which should be the amount of your ram + a couble of MB. And i also think you should have APM support in your kernel.
Otherwise check
http://www.linux-on-laptops.com/ Itīs surely descriped there, just port it to your desktop computer
-Sorry for the lame answer
