
There are pretty much three basic ways to wire wafer paper petals, all of which mimic gumpaste methods.
One is to sandwich the wire between two pieces of petals, which will give you a more opaque petal.
The second is to use a small piece of wafer paper to cover the wire on the back of the petal where the wire is.
The third is this: Get some gum glue, wires and petals.

Dip the wire in the gum glue

Stick the wire onto the back of the petal. The bumpy side of the paper is the back, since that will stick better than the smooth side.

Let the gum glue dry VERY well before you try to mess with the petal.

Remember to let the petal dry VERY well.
The wire will come off if the gum glue isn’t dried securely to the petal.
Also, if you need to bend the wire be very careful since bending the petal can make it break or rip.
If the petal was colored before you put the glue on it the color will darken on the spot where the glue touches the petal.

Sandwich wafer paper wiring method.
The second way to wire wafer paper petals is similar to my sandwich method of wiring gumpaste.
This puts two of the same-shaped pieces of paper together to make one, and sandwiches the wire between the two pieces.
This will make a petal that looks waxier than a single thickness, and it feels a little like styrofoam when you’re shaping it, so it isn’t quite as fragile as a single piece.
First, get two pieces of wafer paper that have the same shape. (Cut them out together to make sure they’re the same.)

Next, coat one petal with a thin layer of gum glue, piping gel, or a very light coating of water.
Don’t make it too damp because the paper will start to absorb moisture from the liquid and buckle if it’s too wet.

Put a wire on the petal.

Place the second petal on top of the first, being careful to line it up exactly on the edge.
Once it’s put in place it’s going to be hard to move it, so try to be as accurate as you can the first time.

Now you have a wire between two petals. The paper should be getting soft at this point.

To give the petal a cupped shape, pinch the base of the petal.

As long as you didn’t get the petal too damp, you should be able to press it into shape at this point. You can twist the edges to give them some movement.

You can also put the petals on a former to allow it to dry with a certain shape. Let them dry completely.

Once the petals dry you can use them like any other wired petal.

Experiment with the different types of glues to see which one you prefer.
The piping gel and gum glue dry stiffer than water, but don’t make the paper shrivel up as much.