First step:
run setup.exe with -X arg
example setup-x86-2.874.exe -X 

Second step:
Use legacy repos:
for win32: http://ctm.crouchingtigerhiddenfruitbat.org/pub/cygwin/circa/2016/08/30/104223
for win64: http://ctm.crouchingtigerhiddenfruitbat.org/pub/cygwin/circa/64bit/2016/08/30/104235

Full legacy repos index:
http://ctm.crouchingtigerhiddenfruitbat.org/pub/cygwin/circa/index.html
http://ctm.crouchingtigerhiddenfruitbat.org/pub/cygwin/circa/64bit/index.html