Custom Lightmaps for HL2?

[LightGun]

Hi Community, I just started with mapping for HL2 and would like to know if there is any way to replace/ or add custom
lightmap textures from/to extisting HL2 maps.. I just like to render some 'better' GI inside 3dsmax to replace
the actual static lighting.. are there any limitations for doing this?

 

[Maui]

In a technical sense it would be possible, but you would have to decompile the .bsp files (illegal I think, but I'm not sure), find the data on the lightmap, figure out that setup, then replace it with yours and recompile. I certainly don't know of any tools to do this. Actually, never heard of a demand until now

 

[LightGun]

hmm, anyway possible to bring geometry from HL2 into 3dsmax or Softimage? any XSI users here?