Not sure about DX input and how it intigrates with the other applications. However The 9630 should have native support for Chinese, Japanese and Korean input. At least that's how it appears when you look at the CJK loader file. In practice I have yet to get any of these language inputs working.
After many hours of scavenging the web for a solution I have turned up empty handed and decided that the only way I am going to get Asian language input support is to take it upon myself to develop a solution. I am not blackberry developer so this may not be a pleasant path to take.
If you would like to see the progress I have made so far you can turn your browser to this page:
Japanese Romaji input Blackberry Tour - BlackBerry® Tour™ 9630 - BlackBerry Support Community Forums
And Please if you can offer your assistance/advise/pr a all out solution then do not hesitate. It will be welcome.