Mission accomplished! Still a bunch of rough edges to work out, and I need to build equivalent blocks for other line codings as well as a "generic" ILA that just records waveforms.

But here's a simultaneous cross-trigger of the SERDES ILA and an analog waveform capture of the signal going into the SFP, (manually) deskewed and aligned.

Now imagine extending this to additional debug blocks within the FPGA.