Thanks for the advice guys that´s all usefull things to employ.
I tried to rubb the seeds of Puna subterrranea, Miqueliopuntia miquelii, Mahuenia poeppigii and M.patagonica on sandpaper by holding them with two fingers -but in half of the cases I lost the seedgrain by twitching it out of sight.
, Then I tried to cut into them with a scalpel and twitched away sonme more (especially the Miqueliopuntia miquelii were tough as hard wood). The I used a woodcarving cisel for cutting with best results. Although in some cases I cut the seeds almost in half they still seemed to germinate good.
Today I tried to squeese and crack the shell of Maihuenia with a forceps and sowed them after powdering with atiram.(Lost only 1 of 8 by hoppping away
I tried freeze and thaw in the baggy for about 3 weeks with maihuenia poeppigii seeds from habitate (ordered from Juan Acosta)- but so far none germinated after 2 weeks in the propagator. Maybe I will try to take them out and make a cut in the shell ?!?