Hi, #1 the bb mini keyboard can only be paired to one device at a time. To clear any current pairing, turn on the keyboard and then hold the control and delete keys down (at same time) for about 10sec, power switch light should start blinking. Then turn the keyboard off.
#2 go to your z10, swipe down from the top to bring up the menu screen, select bluetooth, make sure bluetooth is on and discoverable is on
#3 turn on the mini keyboard, you should see a peripheral listed and then it will say minikeyboard once it discovers the keyboard
#4 a pairing number will be displayed, you have to enter that using the number row on the keyboard and then hit enter on the keyboard
#5 enjoy (works very well, but not exactly like with pb, plus now it will not work with your pb, so will have to do step #1 to clear it again before repairing with pb)
A little long winded but hope it helps, cheers