Manually add missing icons for hdd-osd

[dskw]

Hi,

I've used the batchkit to successfully install my PS2 and PS1 games on the internal hdd of my PS2 fat. Some of the titles do not show a proper icon though, like SLES_013.00.The Unholy War

I was wondering how I can specify an icon on my own, or where the tools even get the icons from.