I am an organic chemist and not a doctor so my suggestion is made purely from a chemical viewpoint not from a medical one. However, the idea occured to me that if magnesium silicate could be altered at the molecular level then it might be easier to expel it. We have these wonderful compunds known as ion excahnge resins which are used in everyday things like water softening agents. My suggestion is that if somehow this type of product could be introduce to the area where the asbestos resides (using e.g. a stearate) then it might be possible to exchange the silicate group for a e.g. stearate. This already happens in nature as magnesium stearate is commonly known as soapstone. Soapstone could be readily expelled from the lungs as it is a different compound. It seems logical that then silicate group would then be easier to expel.
Hope this idea is encouraging. Sorry that I cannot advise from a medical viewpoint.