It doesn't, I figured out a way of doing it without removing the dashboard.
I took inspiration from these two videos, and sort of joined them together in my head. (On the second video, he couldn't get the blower motor out).
You can split the blower motor into two halves. One half with the squirrel cage and motor, the other with the back plate.
So, I took the top panel off (the one behind the steering wheel).
The bottom of the plastic surround that goes around the steering column.
The plastic panel above the pedals.
And the air vent that goes to your feet (see the second video).
(You don't need to remove any pedals on the Twingo, there is just about enough space to get around the pedals. Also the motor is just held on with a tab, push on the tab, then spin the motor about a 1/4 of a turn clockwise and it comes out).
If you watch the second video, have the blower with the squirrel cage point down at the pedals (as in the video).
Then watch what the person did on the first video, pull the tabs back on the blower motor and split it in two.
With one arm under the dash, and the other going through the top of the dash, pull the blower apart.
Put the squirrel cage half back in hole where it goes in the dash, and pass the back plate pass the pedals and out.
Then pull the squirrel cage out pass the pedals and out.
Split the new replacement motor in two before you try and put it back in the car.
Feed the back plate pass the pedals. I left it sitting on top of the steering column until you need it later.
Feed the squirrel cage half pass the pedals.
Now, you need to look to see where the connect is on the motor. Get your back plate, line up where the hole for the connector is. And push the whole blower motor assembly back together.
Put the motor back in the hole that it lives in, plug the connector back in, put the vent back on and put all the plastic panels back on.
And voila, all done with out removing the dash.
(I checked the resistor and connector last week. A lot of places say this is most common reason why its not working on Renaults, so check them before you spend money on parts. On on my car the resistor and connector were fine. No damage at all on the connector or wiring).