Jon - I have to wonder if timing is every meant to be checked. Think about it - it's all computer driven. The reference sensor should pick up the correct timing and the ECU fires the plug. The only timing mark you really need is mechanical TDC for assembly.
At least - that's how I think BMW might think about it when designing these engines.
Building your own ignition and fuel injection system is just a bit outside of what they were planning for I think.
Sure there's a way to do it but I suspect it will take some creativity.
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy