If you do it before you ride it at all it's not to bad, 2 to 4 hours depending on how much time you take. Just slide out the inner race, wipe the old grease away and apply the new stuff. If it has been ridden you may need to do some cleaning with a solvent before you put the new grease in. And as Buckholz says, make sure you use a torque wrench when you put it all back together.
Yup, coupla hours-max. I had already yanked the rear wheel to lace up an 18" rim, and my chain was removed, replacing with an O-ring.
So, just need all the necessary sockets to access the bolts. The swingarm will come out without removing rear brake pedal if you hold the brake pedal down with one hand while removing the swingarm bolt -- you have to rotate the bolt slightly as you remove it to avoid the rear brake arm -- have a helper ready for this although I was able to manage by myself.
I got the 3% moly grease from NAPA - they stocked the Valvoline Palladium. Yamaha specifies moly grease.....