I don't consider myself as an expert..
Our days "experts" are hard to trust.
It is possible to change the cam chain without taking of the left sidecover in theory;
-Camshaft on dead point
-With a special tool; BRAKE up old chain as you would do with a drive chain..
-BRAKE new chain or buy open one
-Attach new chain to old chain with something that wont fall down in engine! little screws and bolts maybe..
-hold the chain tightened on the teeth of crank wheel and turn crank by hand until new chain has taken place of old...AND DONT MOVE THE CAMSHAFT DURING THE OPERATION.
-Press together the new chain with "very special" tool.
-Put on chain to camshaft wheel as you memorised when braking, exactly on that teeth.
An expert could probably do it eyes closed, Though I think all of it is a dangerous option for a normal person.
If your bike is a XT, prefer taking off the alternator and doing it well.
And don't hit the crankshaft, the XT have enough bearing problems that side without hitting them.
If you have some pennies to waste;
Buy the special alternator extractor tool from Kedo in Germany 50€ shippment included, its a great solution cause you'll be able to take that wheel off with ease, according to Kedo; "taking off the alternator becomes a child game".
So instead of buying tool for cam chain, buy that instead, a less expensive option is to build the tool yourself.
To do a perfect job; the chain slides in plastic should also be changed cause they deteriorate with time as well..
Hope it helps,