Publications below by Douglas R. White, esp. 1983, explain the method. Exact significance tests are computed for 2 by 2 contingency tables and for 3-way or 2 by 2 by 2 tables (significance test of 3-way interaction):
1994 Fisher-B: A Program for an Exact Significance Test for Three-Way Interaction Effects World Cultures 8(2): 40-43.download fisher-b.exe (c) Douglas
R. White as Shareware
Fisher-b Manual