If you are using Rez Hacker then simply copy and paste.

Ok, scroll down to the hair bobbles and change the -1 at end of the line before the new hair ball to 2 on everything you want to have the bmp except eyes etc.

63, 65, -60, 0, 46, 244, 0, -1, 0, 2, 30, 8, 0, -1,

becomes...

63, 65, -60, 0, 46, 244, 0, -1, 0, 2, 30, 8, 0, 2,

Scroll up a bit to the textures list and change the \art\autobuild\cottonwhite.bmp 0 to \resource\clothes\nameofyourbmp 0

For example...

[Texture List]
\art\autobuild\hair3.bmp 1
\art\autobuild\clear.bmp 0
\resource\clothes\abs_bobble1.bmp 0

Featured baby has Cotton Blue hair bobbles which are found at

\art\autobuild\cottonblue.bmp