At week 5, your plant's in motion to make flowers. Success of rooting would depend on how tempermental your strain is (for rooting), also your strain, as indicas and sativas are on different time clocks before the end, and conditions.
It would not be my choice to try to root at week 5, but it sounds like you have no choice.
I would say pick a nice healthy couple of cuttings around 4" to 5" long. Top or midway down the plant. Lower cuttings may work, but they might be light starved, and may not have enough stored energy to stop flowering, and make roots. Use root hormone, and give it the same conditions as a normal clone or cutting for rooting. Optimum temperature would be around 80 deg F. Below 70 degrees with an already stressed cutting in flower my keep it or them from rooting.
Didn't mean to get long winded. Good luck.