vertexpaint from material ?

I am not sure if this is the forum to post it. If not, can a mod move it?

Anyway, I really need help here, so I appreciate any directions.

What I need: to populate a plane with instances from a group based on a bitmap texture. I mean, white parts of the texture should have many instances, grey parts should have few and black parts should have none.
Like in this right example (except that the particles are objects to remain in the ground)

What I found: Blender used to have the ability to do this, but it was lost before 2.49 (it seems to still work with files created in 2.45 with this feature, but I can not create new files with this because there is no longer the “texemit” button nor the area it used to be located), so I can not use the native implementation. Then I found that there used to be a script that could convert textures to vertex paint here but I can not find it anymore and/or make it work. Nor in blender 2.49 nor 2.54

What I ask: That someone would tell me, in order of importance:
-how to achieve this like it could be done in 2.45, but, if possible, in 2.5x. Or if not, at least in 2.49x, using actual bitmap textures set to control the time/density/so on.

-where to find/how to use the, if possible in 2.5x or at least 2.49x. Then I could subdivide the geometry a lot and convert the texture to vertex weight and use it to control the texture. This is far, far from ideal, but it would work.

-how to do this any other way, as long as I use the bitmap as a base.

This quite important for me, so thanks very much if any of you can help me in some way.

No one knows?
Maybe I should post in another subforum?