http://www.dstorm.co.jp/dslib/dx3d/DX3D_132.zip
If you goto the Flay website they have a search engine there for the plugins which is very good.
When you have the file, unzip it into your Lightwave plugins folder or anywhere safe on your hard-drive then run Lightwave (layout) then goto Layout\Plug-ins\Add Plugins and goto the folder you unziped to and open the DX3D_132\Windows (this is for the latest version 1.3.2) folder and select all 3 plugins that you see, and click ok and it will come up that you have loaded 6 plugins. What i normaly do now is close layout then open it again as this will save the info of the plugins being loaded incase your programme crashed and you would have to do this again.
Now, to make it easier to find the plugin what i have done is create a tab for it on the Items menu so it is easier to use, so, to do this:
Goto layout\interface\edit menu layout (or press Alt + F10)and the configure menus window will open, on the right side open the Main Menu tree then open the Items tree, clickon the bottom item (should be IK) then click on New Divider on the right, then click on the new divider you created so it is selected and on the left window open the File tree and select Export DirectX(.x), you should have 2 things selected now, all you have to do now is on the right side click on Add then click on Done and you will see the new tab on the bottom left of your screen. (hopefully

)
When you goto use the plugin, when you open the window where it says Version put this to DirectX 8 and stick the Format to Text.
I don't believe there is any english docs for it but any problems with it just let me know or ask someone else on the forums.
Hope this is of help to you.
Cheers.