[tlinux-users:08250] Shift the keyboad to "PgDn"/"PgUp" function

Hi, I am not familiar with the Japanese system of Keyboard, currently unfortunately, I have to use the laptop of such a system,  any one could be kind enough to tell the way how I can use the "PgDn"/"PdUp" key which are overlapped on the same key of the arrows? I am using Dyna SS book series
 
Thanks
EGao