If you can't move out of the way, move into the punch with your forehead. Much stronger bone structure than nose or cheek. Since a good punch is strongest and fastest at a critical poitn, and the slugger is braced ofr it, reducing the travel distance of the punch by a few inches can help.
Read it somewhere, never tried it. Same place gave advice for taking a blow to the stomach - angling so that it hit along the plane of the abs to absorb the shock.
Being tied to a chair doesn't work so great with any techniques - your assailant will just punch again at his leisure.