So yesterday I started the charging process. Decided to take it slow due to not knowing much about the Li-MnO2 cells (I'm more of an 18650 guy)
Since the cellpair 57&58 was at the absolute bottom of the stack, they will be extremely hard to get to. I don't want to dissassemble the pack, so I improvised some sticky leads with harddrive magnets inside alligator clips. That way I can just lower them down into the pack, and they will stick to the terminals.
I then hooked up a bench supply, set it to 8.4V and connected it to the outer terminals of the 2S cell. I am lucky that the rest of the pack is at 4.00V cell average, so I wont have to worry about CC/CV switchover, just CC charging up to 4V (8V effective due to 2S). As charge current limiter, I set it to 0.3Amps, to keep temps and everything nice and smooth.
I also disconnected some of the BMS leads, don't know if this was necessary, hope I don't break the BMS by piggyback charging this way.
After 18h of charging, the cells are up from 3.60V -> 3.95V, so just a few more mV to go!