You just need to fill out the
SS4 form and then call the phone number in the instructions to become
registered. The whole process should take about 10 minutes.
When you call into the IRS office the
operator will ask you "...what is on line #1 of the SS4 Form,
what is on line #2 of the SS4 Form, etc."
The number to call the IRS is:
1-800-829-4933.
See below for the links to the SS4 and
the Instructions...