It should be doable.
I did this a long time ago (well over 10 years ago) with my schrick cams, so the exact ins and outs are a bit vague
.
I used a guide on e46fanatics (that guide is not online anymore) and some info from bmw TIS and got the schrick cams installed pretty easily. In my memory it was pretty similar to the guide you're using, I'm certain that it was with rotating the cams a bit to ease off the tension on some of the lifters.
I may have a backup of that guide somewhere if I seach deeply in my backups....
The schrick cams obviously have longer and wider lobes, so if it works with the schrick cams, it'll be a breeze with the stock cams
