I think you can.. I'm not entirely sure but you could always test it out? Unless someone else posts about it. But GIMP is a great software for doing presets with. And to change your icon, just go onto where it says 'PROFILE' then click on 'Forum Profile Information' and then choose on of these options:
(http://i48BannedImageSite/2lnbz1y.png)
As long as your are able to save your parts in jpg, or png, then I don't see why not using Paint tool SAI.
The main programs to use by the way is Photoshop and GIMP, but I'm sure there are other softwares that so just the same. Here's a tutorial on how to make a beginning preset for starters so you have a idea.
Feareh's Tutorial:Presets BASICS PART 1 (http://www.feral-heart.com/index.php?option=com_jfusion&Itemid=2&jfile=index.php&topic=31873.0)