I'm not an expert, but this is how it worked for me. I paid first and gave my name and member account number to the seller. The seller then called Member Services and requested that the points be transferred to my account number. It is pretty quick and simple.
Banked or borrowed points cannot be transferred. Transfers can only go one direction in a use year, so if you transfer points out, you can't also transfer points into your account in the same use year. Points are supposed to retain their original use year and home resort, but in reality they seem to take on the use year of the account being transferred into due to computers not being able to separate them. Member Services can track them manually if necessary.
