Gaussian fit in 3d? Need a direcction ...

[Ironic Prata]

I?ve posted something similar to this before, but things have changed a bit so i am trying again.

I need to multiply several 3d probability distributions. The end result is a probability blob in 3d.
I want to aproximate that blob to a 3d Gaussian (x,y,z coordinates and value in the 4th dimension).
My ideia is to sample a few points in and around the blob, and use them to fit a Gaussian to obtain the parameters.
I have some skills in matlab, but am new to fitting, and since all i could find was for 2 dimensions, i was hoping someone could point me in the right direction.

Thank You.