This is a DIY job but with moderate to upper skill level and knowledge. Great care must be taken with timing mark alignment and tensioner adjustment or engine damage will most likely result.
Start by removing the 2 T30 torx screws for the top spark plug cover and remove it. Then remove the 13mm nut holding the power steering line bracket and lightly loosen the 16mm flare nut on the pump pressure line. Now rotate that line upward and on top of the plug cover and snug nut back up to hold it's position.
Next I like to remove the 2 10mm bolts holding the pump reservoir in place and move it aside. Remove the 10mm bolt securing the top half of the belt cover (where my finger is pointing). Lift straight up and out of the way.
Now with a floor jack and a block of wood on top. Slide it under the oil pan and as closely to the corners/edges as possible. Do not dead center it on the oil pan as the middle is the weakest point. Use a 2x4 or such that will span the entire pan side to side. Apply light pressure with the jack, now go back up top and remove your 6-15mm bolts (2 nuts) securing the mount to the frame and the motor. Remove the mount and set aside.
I'm removing the center mounting bracket on the motor for ease of pictures. This does not have to be removed when doing the job but I recommend it. You will need to remove 4-13mm bolts and the one mounting stud(red dot next to it) in order to get the upper bolt removed. This bracket is dowel pinned so you may have to wiggle it a bit once the bolts are removed.
Now use a long 14mm wrench and release the serpentine belt tensioner, remove the belt. With the belt out of the way you can remove the lower half of the timing cover by simply pulling out and upward (it slides into grooves on the rear cover)
Remove the right front wheel and remove the 2 bolts holding the plastic side cover in place. Take the side cover and flex it down under the front of the car to expose the crank pulley.
Now reinstall the spark plug cover with the timing mark cutouts and with a 30mm socket rotate the crank and bring the motor up on TDC. The cam marks are very difficult to see (yes they are there) they are tiny hash marks so I paint marked them for this documentation. Align the cam gears straight up with the 2 cutouts on the underside of the forward spark plug cover. With it all in time go back down and remove the 4-10mm bolts and the 30mm crank pulley nut. (An impact gun is recommended for this).
With the pulley bolts removed go back up top and with a nice size pry bar. Slide it between the back of the crank pulley and on the front of the timing belt tensioner. Pry towards you and the pulley will be released. This is not a good picture but the dark shadow in the middle is the pry bar.
With the crank pulley removed I paint marked the crank timing mark that should be aligned with the pointer on the oil pump housing. If your timing marks are not aligned you may re-install the 30mm nut and rotate the assembly into time again.
Now I like to pull the belt snug on the intake side and recommend you lock your cam gears together. I'm using a cheap universal tool (and actually my favorite one) to do such.
Next you want to loosen your 12mm bolt holding the tensioner in place. I just remove it all together as I ALWAYS replace the MANUAL tensioner with every job. This is an absolute MUST on the S40/V40!
I remove the top forward spark plug cover again and remove the belt. Install your new tensioner loosely and then the belt. Slide the belt around the crank first, working the belt counter clockwise around your gears and idler pulley's keeping it taught on the intake side. This can be a bit trying sometimes and it will be a tight fit. Once the new belt is on remove the cam locking device and your ready to adjust the tensioner.
With the 12mm bolt lightly snugged use a 6mm allen wrench and rotate the eccentric clockwise to a full stop. Return counter clockwise until the pointer reaches the ambient temp the motor is at. I HIGHLY recommend doing this job with an ambient motor temp of approx. 70 degrees F. At this temperature the pointer should be about centered. The chart above gives you the variables. When you have the pointer where it belongs lock down your 12mm bolt. If you miss your point on the return direction you must start over again and go to full clockwise stop then return to your point and lock down the bolt. This process is also a bit tricky at times. Now with the new belt on reassemble most and rotate the crank 2 full revolutions and re-check all marks. If all is good reassemble the rest and done!