Lets say that I want an AL frame that does not have downtube bosses. (I like DT shifters). Lets say that I buy some steel bosses of AL threaded tubing.

Can I have the bosses friction welded to the frame?

OR

Would it be better to weld a piece of AL threaded tubing into a drilled hole in the DT and thread the shifters onto that?

If I drill through the frame would that compromise the integrity of the frame?