I just took this video of myself servicing an E61 espresso machine group.
It took me 20 minutes or so but if it's your first attempt, allow for an hour (plus). You can do the service with a few tools - you will need a large crescent wrench if you don't have a 36mm wrench for the upper and lower assemblies.
In this case, the components were not worn so I only used a 'soft kit.' A worn E61 will benefit from a full 'Rebuild Kit.'
Be careful to organize the springs and valves together when disassembling as it is easy to mix them up later.