Bizarre question. It is ordinarily necessary for salvation to be baptized (John 3:5), obey the commandments (Luke 18:20), do works of charity (Matthew 20:31-46), have total dedication to Christ (Luke 18:23), partake of the Eucharist (John 6:54-55) and confess sins (James 5:16, 1 John 1:9). Praying to Mary is not mentioned among these necessities. Reading the Institutes is not mentioned either.
A Christian is judged by his works (Apocalypse 22:12). This apostolate is open-ended: at no point can one say "I did which was commanded me" (Matthew 25:26-30, Luke 17:6-10). This is why a Christians seeks mentors in his life. Mary and all the saints are there to offer us the example of their Christian lives and to sustain us with their prayers. Is it necessary to look for them and ask their prayers? No; it is merely foolish not to.
"Mary and all the saints are there to offer us the example of their Christian lives and to sustain us with their prayers"
The only example of any one being asked to intercede with God for another after they have died, except the risen Lord, is Saul's requesting Samuel to find out what the future holds in 1 Sam. 28:15. Samuel's response is what is to be expected, "Why are you bothering me?" The deceased saints have better things to do than worry about us here on earth. Look at the book of Revelation. The deceased saints are minding their own business praising God while God is displaying His wrath on the earth and its inhabitants. There is no evidence of saints interceding for the inhabitants, in fact, it is the martyrs who are asking when God will exercise His final judgment and end the suffering.
We, who have trusted Christ for our salvation, are saints, now, and of equal value to God and have as much access to God, by faith, as what we would consider the greatest of saints who have gone on before. God is no respecter of persons!
How do you speak to the dead?