Yes! You may purchase a home in CA with your son's name.
We would have him be the principal on the loan. From the inception of the loan, we would have your son make the payments from his own account. As long as we can show that he has been making the payments (and on time), then that payment will not be counted against you when you go to purchase your retirement home.
If your son is a student, you may also utilize his name on the loan to purchase as an owner occupied. Thus you can get into the property with ownwer occupied rates and owner occupied terms.
Best methods of finance would depend on down payment, etc.
If you could send more details, I could point you in the proper direction!! :)