dont know about removing the s spoiler but i added it to my ONE. fairly easy install. but, beware it will make you a little sqwermish if you read on!!
firstly unpack it!!
then using some sand paper - faily coarse! start to sand the paint off the inside of the spoiler so the side that touches the car has no paint on it. i only sanded up to the tape on the spoiler see pic 3
then using masking tape mark out on the boot where the spoiler wants to sit. (see pic 1 +2)
now using very fine sand paper (this is the bit that youll like

) sand down the boot staying about 1cm inside the line of where the spoiler sits. (i know i didnt want to do this but good old dad comes in and goes "E R DO IT LIKE THIS") only sand the top laquer off not the paint!!!
now use the special wipe solution supplied to wipe the spoiler down on the non painted side!
put the glue on the spoiler aprox. 1cm from the edge (you will see the lip running around the perimeter of it)
now use the special wipe solution supplied to wipe top of the boot where the spoiler will sit.
with the help of some one else align the spoiler up and press on!!
pull the masking tape off trying not to move the spoiler
stand back and look what you done

see pic 5
i used two bricks (half on the spoiler and half on the roof to hold it in place while the glue set, OBVIOUSLY I USED PLENTY OF CLOTHS UNDER THE BRICKS SO I DIDNT SCRATCH THE ROOF ETC..) see pic 4
then once all this is compleated leave for at least 8Hrs before using and at least 48Hrs before washing your car or going through a car wash. it will be ok to take out after the 8Hrs.
total installation with out drying time was about 1.5Hrs
hope this helps