so are you, >_>. (aimed at shader)
k ill keep it short,
im assuming you want to convert a bfp model.
decompile the esf model you want it to replace to a folder on your desktop
bfp models are generally divided up into 3 peices, head, torso, and legs
import all 3 peices
now position the head at the neck and the torso at the top of the legs, so its all standing up and such.
usually bfp models are pre-posed. you will have to work this out yourself. select the verts and rotate them to your desired position. (you will most likeley give up at this step)
after that import your esf skeleton, from the folder on your desktop
scale the model to fit it, then assign it.
export it to that folder as a reference smd over the existing one.
resave the textures as the proper format and put them with the model
now tools>half life>compile qc file. and your done
(note its been awhile since ive done this but most people with even a little knowledge of milkshape should be able to fill the gaps)