done this twice on my XTZ... my OoO...

split the chain in the middle of the lower run...dremel or grinder with a cutting wheel is good...LEAVE THE CHAIN IN PLACE after splitting

front sprocket removal is tricky, you'll need to lock the sprocket in place to get the nut off...

next, take the end of the chain that is dangling off the rear sprocket and bring it up and around the sprocket to meet the top chain run, and thread a suitable size, long and thin, bolt through a set of links to hold the loose end to the top chain run, screw a nut on to the bolt... this effectively locks the front sprocket so you can apply the necessary torque to get that nut off

its a bit hacky but it using all the old stuff you are throwing away, so no worries and i believe it prevents you from damaging the gear box by putting the un fastening torque through it, and this way you can do it all yourself with out someone standing on the rear brake

un thread the chain from the front sprocket...leave it on the rear for now...fit new front cog, screw on the nut

now repeat the trick with the chain and bolt but you'll need to figure out which way to loop and bolt the chain to allow you to torque the nut CW

once that's done, rear wheel can come out

leave the sprocket carrier in the hub...easier to undo the nuts...simple replacement once you get this far

cant remember all the torque values offhand..but they're in the manual...

have fun