I have created a config for my favourite PDF viewer xPDF. The main goal was to navigate with hjkl and give it a little bit of vim feeling.

You can save this little config i.e. as ~/.xpdfrc:

continuousView yes

bind O any toggleOutline
bind h any scrollLeft(20)
bind j any scrollDown(20)
bind k any scrollUp(20)
bind l any scrollRight(20)
bind J any scrollDown(60)
bind K any scrollUp(60)