ahhh i got beaten to the plerophoria shout.
I tried this a couple of months ago. I ended up with a floor full of small bits of paper, a cut finger, glue everywhere, and a useless notepad that wouldnt hold any cards. FML.
don't let me put you off though, I'm really inept at this stuff, I'm sure you'll be fine. Im pretty sure derren recommends cutting out the back of the pad so there's a card sized hole, then bulking up the thickness with mounting board and just ripping out the back half of the pages. I decided not to get mounting board and just cut a hole in each page, this takes effing ages, and when you're done the 'walls' wont be vertical unless you are some kind of genius and its a HUGE pain if the cards are then too tight in the hole. Plus cards can still slip out the side because the pages are loose. BUY MOUNTING BOARD

thats what i am DEFINATELY doing when i get round to my second attempt.