You can follow the same procedure used for the tappet adjustment. It is described in the factory manual. What you do is remove one bearing cap at a time (there is a specific order, otherwise you may snap the camshaft), replace each bearing cam with suitable spacers, retorque the cyl head bolts. In this way you avoid to unsettle the head gasket. When you have removed all the bearing caps and the camshaft is free, you can replace the bearings, and replace all the caps, one by one following the reverse procedure.