Nothing to it...
Just be careful pulling it off. Yepending on which side, you have to move stuff out of the way to get it off. Be careful not to overtorque the bolts putting them back, and might be smart to replace the crush nuts that hold it down if they are shot.
The gaskets don't cost much. Would be a good time to check out the chain and rails while you are at it. Do a forum search on timing chain replacement and there is a great pictoral on chain replacement on a 560 sel (sames setup as the 560sl, just different body style.) If you are uncomfortable doing the work yourself, might be wise to have a MB mechanic show you the chain stretch and such. Should be about a $100 job. Try to get them to walk you through it so you'll understand what they are talking about.