NOTE: This was done on European 2011 Ford Focus MK3.
This process took me about 30 minutes. I changed the stocked halogen sidelights to LEDs.
Before: Stock sidelights
Pop the hood, remove two screws as indicated. Gently wiggle the headlight housing up and out. Take care as there is still a wiring harness attached
There is one wiring hardness at the centre of the housing. Detach it, and the headlight housing can be pulled out of the car completely
Headlight is out of the car (left headlight)
Remove the indicated rubber grommet from the back of the headlight (this is the right headlight)
This is what it looks like behind the grommet
Get some needle nose pliers or use your fingers (difficult) to pull the bulb holder and bulb
Pull out the stock halogen and insert the LED
Before you reinsert the bulb assembly into the headlight housing, plug the headlight wiring harness back in and test the light. These bulbs can go in two ways but only one way works.
After: LED side lights
The picture makes them look a lot brighter and blue'r than what they are in person.
Hope this is helpful to someone.