Old thread but interesting addition, maybe. Chain guides on cylinders 1-4 may not require heads off after all. From my parts browsing and realOEM I noted that the pins that cause the issue are separate parts and could be sacrificed and replaced. Dremel the pins off. The install guides with new pins in one go. It really depends on how much wiggle room is needed for installation, but it could well work.

Parts 8 and 11 here:

https://www.realoem.com/bmw/enUS/sho...diagId=11_3267