Denesta in ghost form
"Feel free to come in."
"But you wont be leaving."
It is done the same as the ghost NPCs in the game such as the Nightmother. "player.saa 0.01" and "player.pms 00b9932" 00b9932 is the ID for the ghost effect shader.
"player.pms 00b9932" - Oops that is 000B9923
PMS stands for "PlayMagicShaderVisuals" it is just a short cut so you don't have to type the whole thing out. What it does is place a shader effect on the target.You can find those in the CS if you load the Oblivion.esm.
The ID number you need is hidden by default so you need to slide this divider to the right by clicking and dragging.
Then use the listed Forum ID of the effect you want to add it to the player.
As for SAA that stands for SetActorAlpha. This can be any number between 1.0 and 0.0. 0.0 is completely transparent(invisible) and 1.0 is completely solid.
Hope that helps
(Note: Click on the above images to make more legible.)