you should check the following, if you have not already done so:
Payment: some insurance companies may balk as this is unapproved AND expensive (probably $10-20K per month). Have you tried other treatments?
Availability: IVIG is still in short supply and usually allocated to Pharmacies, so your doc may want to see if he can actually get it for you.
Location: this is a 4-6 hour infusion so it is done in a clinic, hospital or perhaps office. You will probably need the day off.