Well my replacement SS4200 has arrived surprisingly swift. That left me a lot of time to tinker with the serial console part again, but I couldn't get it to work. I noticed that the BIOS on this unit was a different version than the old one, maybe that's why.
The trouble is that you need to access the BIOS to change the boot order. But as soon as a new disk device is recognized, the boot order is changed. Bummer. The nice workaround that I used was to utilize SATA hot-plugging. Although it's specifically not supported with the EMC firmware and also it's stated to be unsupported in Intel's docs, it works surprisingly well. ;-)
In case anyone needs to know: First plug in the power cable on the drive, then attach the SATA cable.