By custom wallpapers, I am assuming you mean the background image? Yes you can, just touch and hold for the desktop menu and select wallpaper. If you want to load a custom image from your PC, make sure to re-size the image to 960x854 pixels for max resolution. And then drag and drop of course.
The wallpapers posted in this thread are all designed for Home++ or other looping home apps. Each image at full crop size allows you to scroll across all your screens without encountering a seam between image edges. Effectively, they are spherical or cylindrical wrapped images.
I started making these because the seam bugged me but I *love* the looping space. I'll be posting some more in the next few days...would love for other home++ aficionados to jump in =D with what they're using, or if anyone has any requests or source photos...