If '93 is like '95, the plastic wire holder has two 3/4" wide plastic clips that snap under the edge of the front rocker arm cover. The clips are molded as part of the wire loom. You can feel them with your hand and see them with a mirror. Just pull the clips outward at the bottom and lift. The whole piece just slides off on tracks that are molded into the cover.
The clips snap under the bottom of the valve cover close to where it seals against the cylinder head.
When you install it, you just set the loom with the wires installed on the tracks on the cover and push down until those two clips snap into place to hold it down.