You gonna hate me because I told you this. If I recall right you do have a copy of MBusa service cd-rom. On this there is a pdf on adding a oil nozzle that sprays oil on the chain itself. The oil nozzle was added to later model w201 engines.
That a look and if you don't find it drop me a mail. This is maybe not an easy addon but maybe it's worth the effort if you're planning to use the car for a long time. Just my 0,02 cents
And if you don't have the ratchet type tensioner maybe it's a good idea to get one. The difference is that this type tensioner will keep tension even thou there is no oil pressure on it. Less rata-rata-rata sound when cranking up engine