I'm brand new to pixelpost but I think what your asking is already there on version 1.7. I just installed the program last night then uploaded a few pics just to experiment with. When you have chosen your category then your first pic from the thumbnails the "Next/Previous" links appear with the photo. Hope this answers your question, choose a category from here --->
Click Here and see what I mean. Site is very basic just now so excuse any errors.