Assuming you are charging the same type of cell with very very similar capacity and internal resistance in series, (NOT LiMn and LiCo cells together at the same time), then you can charge in series, but I don't recommend it unless you put the balance taps in place and use them. With balance taps in place, it's perfectly fine to charge any number of the same cells in series (within reason I suppose).... Without the balance taps, one of the cells may suffer from some over-charge. The LiMn cells would be more tolerant to this.
make sure to set your charging rate to about ~0.25-0.5A for the LiCo Powerizer cells, The LiMn IMR cells can be charged at up to 1.5A IIRC.
balance taps are what the charger uses to isolate individual cells on the circuit to check their voltage and top them off independently to prevent any of the cells from being overcharged, and to keep the entire pack balanced. It only applies to charging li-ion cells and has nothing to do with Nickel chemistry cells. I have no idea of the triton has support for balance taps or not. Again, it would be MUCH smarter to charge your loose li-ion cells in PARALLEL with the charger just set to "1 cell" output. This will result in balanced cells without the need for all the additional wiring associated with balance taps.
Don't charge li-ion in series without balance taps if you can avoid it. It can be done a few times as long as the cells are very closely matched in state of charge and capacity, but each time you cycle a set of li-ion cells in series without balancing the cells, the cells are likely to get farther and farther out of balance, eventually leading to a cell that is getting routinely over-charged, which is not ideal....
Some people have reported greater levels of success doing series charging of li-ion cells without balance taps than others, the only way to know how well it's going to work for you is to use a multi-meter and monitor the charging and see what the results are.