Revracer

So my new Koolstop pads came for the Weinmann 605 brakes on my PKN10. It is clear they pads want/need to be slid into the 605 cartridge. Of course both ends have a tab bent over and they don't use a screw to lock pads like new models. Before I start jimmying the tabs with a screwdriver and pliers, am I missing the easy way to swap these?

Chombi1 

Bend over one of the tabs at the end of the holder get a flat blade screwdriver tip between the old pad and the holder and lever out the pad end from the holder. You can then grab the pad with long nose pliers and peel it off, away from the holder. Don't bother trying to slide the old pad out as it will he a PITA to do so. You will need to slide in the new pad though, as it will not go in the way the old pad was pulled out. If you have a bench vise, with careful set up you can use it to press/slide in the new pad into the holder. If you do not have a vise you can tap in the new pad with a mallet or hammer. A bit of liquid soap will help get it in easier. Remember to bend back the tab on the holder to make sure the pad stays in.

Narhay

Are the current pads original or replaced long ago? All the pads that I have replaced have had one open end on the holder.

Revracer

Thanks @Chombi1, the pads appear original so not bended ends.

dddd

Depending on whether or not the bent tab still seems strong after bending, I would consider drilling a small hole for a tiny retaining screw, in the manner of modern pad holders.
Having the screw threaded into rubber should act as a retaining elastomer, so the hole for the screw seemingly wouldn't need to be tapped.