These instructions specifically deal with a side-mount footrest Invacare Storm Torque Wheelchair.

It is easiest to mount to a wheelchair when the chair is unoccupied

Determine the mounting side for best access. (consider avoiding the wheelchair controls)
In this example - we have mounted to the left side of the chair.

For clarity, the footrest is removed and the arm-rest is folded up.

For this type of chair, we are going to mount to the seat-rail track.
Before we begin mounting, try to see if there is anything obstructing the mount, and that we have enough space along the track to fit the T-Nut (allow 2 1/4" length)

Locate the socket head cap screw at the end of the seat rail (it holds the cover).
Using the 3/16" Hex Key, unscrew that by turning it in the counter-clockwise direction.

Once completely unscrewed - remove the screw along with the little black plastic spacer.
Do not lose them! You will need them for re-assembly.
Set both of them safely aside.

Mark down the foot-rest extension either on paper or with your camera.
After this step, the foot-rest will come loose.
We will need this measurement during re-assembly.

Hold on to the opposite side of the screw (we will call it a "nut") before you start unscrewing. This ensures that we don't drop that piece once the screw is removed.
Using the same 3/16" Hex Key, unscrew the second screw by turning counter-clockwise.

Once completely unscrewed - keep hold of the "nut" and remove the screw and black plastic spacer.
Do not lose them! You will need them for re-assembly.
Set these pieces safely aside.

Grabbing both the foot-rest and the rail cover, slide both these components out of the seat rail.
Set these components aside.

Now it is time to use the T-Nut (WC-TN)
Remove the T-Nut from the bag, and set the longer pair of screws in the same bag aside - we will be using this to attach to the T-Nut
Insert the T-Nut into the seat-rail track (it can be oriented either way).

This wheelchair has plenty of space between the screw #2 that we just removed, and the T-nut.
We need to ensure that we can still re-assemble the foot-rest.

Now that the T-Nut is inside the track, we can re-assemble the foot-rest.

Insert the foot-rest & rail cover into the seat frame, and attach using Screw #1 and the "nut". Make sure that the "nut" is facing the right way so that both Screw #1 and #2 can be attached.
Using the 3/16" Hex key, screw it clockwise.

Screw in Screw #2 using the 3/16" Hex key, turning clockwise.

Remove the Wheelchair Adapter Plate 2 (WC-AP2) from its bag and position it by the T-Nut.

There are multiple positions and orientations the WC-AP2 can be attached - so position the threaded holes for best attachment of the Wheelchair Bracket.
In this example, the WC-AP2 is positioned so that the wheelchair bracket (and post) will clear the arm-rest.

Once you have determined proper position for the Wheelchair Bracket,
Use the longer pair of screws we set aside from the T-Nut bag to attach it to the T-Nut.

In this example, we attached the WC-AP2 to the T-Nut using a hole and a slot.

There are multiple positions to attach the wheelchair bracket.
In this example we select the furthest position from the user, using the Adjustable Wheelchair Bracket (WB)

Which Wheelchair Bracket to select? Adjustable vs Solid Wheelchair Brackets?

Using the two screws that came attached to the Adjustable Wheelchair Bracket, screw the WB onto the WC-AP2.

Screw both of these clock-wise, using the 3/16" hex key.

Congratulations!
You should now have a set-up that looks like this.

The next step is to insert the post, and attach the mount!
These steps are not covered in this document