@ Red:
Yes I mispell it, according to the
shader manual, it is spelled like Torhu said: "q3map_lightmapMergable".
To disable mipmapping add
"nomipmaps"
in its own line, this is a generic shader command (
see the shader manual help).
Finally, try this switch :
q3map_lightmapSampleOffset distance, this could probably help you, to fix your easygen terrain.
If this still doesn't work... erf.... plant some cactus there

@ Pardner:
No, Q3 engine only support 128x128 lightmap, external lightmap are processed just like any other usual texture, so you can't import it into the bsp (and there is no reason at all to do that).
Probably a trick that work with RTCW, when I was searching for external lightmap information, every tricks I found was only working for that game.