Men don't rape men, they sodomize. Spousal immunity in some old laws has been pretty much done away with. Women may be charged with rape as an accomplice. Agreement between two or more people, beyond an undercover gov't agent, to commit an unlawful act, and some degree of intent. For conspiracy, one overt act in furtherance of the crime by any involved party gives liability.
Ultimate act can be impossible to carry out.
Everyone does not have to know everyone else involved. All parties must have a common end. Individuals are charged with conspiracy and the actual crime, the two don't merge. Acts of one are the act of all. At common law, breaking and entering into a dwelling during the night with intent to commit a felony.