109 key Japanese keyboard

Hi I'm based temporarily in Japan and have acquired a 109 key USB Japanese keyboard for my laptop (running SuSE 9.0). It works fine, apart from the five "extra" keys (backslash, yen-sign and the three "henkan" keys around the spacebar), which do not produce any kind of input. xkeycaps shows these keys do not seem to generate a keycode, except when pressing certain combinations together, which seems to register a press on the CTRL-key. Anyone have an idea how to get these keys working? (While I'm not too bothered about the "henkan" keys I'd very much like the backslash, otherwise I'm limited to using a non-Japanese layout which can be slightly tedious). Thanks Ian Barwick