For the Peanut Shell, I followed the blog's directions and drilled two holes along the top of the seat and two more on the sides. The original design had the holes in the front bar but with Big Brother getting bigger, he already has trouble getting in and out with the bar, I often take it off. I didn't want the poles to poke him in the legs. A couple of grommets and some electrical tape to keep them from falling off (you might want to get tighter grommets) and it was good to go. The front poles don't even have anything holding them in. Big Brother is able to pull them out but the angle that they go into the holes makes it so they don't fly out on their own.
I first attached the back poles with a couple of zip ties and tucked the ends of the poles into the bottom bars of the seat's frame. It is the opposite of the Peanut Shells design where I have a lot of pole in the front and not so much in the back. The Mini Yepp has most of the cover's pole in the back and not as much hanging off the front. For the front attachments, I have the cover hanging over the windshield and am using outdoor Velcro to adhere it on. The little velcro straps of the cover loop around the velcro and are holding, so far. I worry about the heat melting off the adhesive but if needed, I can either drill holes into the Yepp bolster or use ties to attach the cover's loops to the handlebars/Yepp's handlebars. I've even ridden the bike without the front poles attached and unless there is a strong wind, it's not a problem. I wouldn't recommend riding like that always but if the velcro were to come off, you could still get to where you needed to go and ride until you had a chance to fix it.
It is a little more work to get the boys in and out of their seats but not by much. Both designs leave the poles free enough to easily pull out and tuck back in as needed. Big Brother does this on his own while getting in and out. Little Brother can usually get in/out without changing the poles but if needed, I can open the velcro tabs and tuck one of the poles out of the way, opening the cover up. The amount of protection if gives makes it totally worthwhile. As long as my boys are happy, comfortable, and safe, we'll be able to ride forever.