Merge Texture - More details

Lets say I have 3d object like an human body ,
on this object i’m applying some diffrent texture, some of the texture will be blended with each other on the intersections parts,
now that all the textures are applied on the object i want
to save the texture in (one!) bitmap file and of course remap the u,v coordinates of the object to correspond
to the new merged texture.
how can i do it ?