Maybe a solution:
blender can open many formats, and can export to .map, which wed can import
you could make sketchup export to .fbx, .obj or .3ds, import that in blender, and export to a .map file.
you can open this map file with wed.

However, it may be very slow ingame.

i tried to use the export_gs_map.py plugin for Blender and it exports the level as MDL ...

i did not notice that blender has a built-in plugin to export to map o_O

i tried to import 3ds into A8 WED and then save it as : something.map
well it exports to map but i can't open the exported file in any map file editor .. its code is different x_x

anyway .. 'Roel' thanks alot for your big help

**Here Is The Solution :

*Get 3DGS A7 or A8 Free/Trial Edition

1-Start a new level in A7/8 WED .
2-Import your model .
3-Save Level as yourlevelname.$$m .

*Now you can open your file in A5/6 WED ..

Thank you all