How to dialkylate a cyclohexene, and convert a carbonyl to an alkene?
You are right about using the Gilman in a 1,4-Michael addition. The enolate created from this can then be used in the nucleophilic attack of a haloalkane. Then all that's left to do is a Wittig reaction, swapping the carbonyl oxygen for a carbon. The full stepwise synthesis would be: