Microsoft Interop Office Word - MultiLevel List

Question

How can apply MultiLevel List to the Table of Contents  generated?
ie  I want to number the TOC like 1, 1.1, 1.1.1 etc?

1.       Chapter - 1. 1

1.1.    Section - 1. 1

1.1.1. Part - 1. 1

1.1.2. Part - 2. 1

2.       Chapter - 1. 2

2.1.    Section - 1. 2

2.2.    Section - 2. 2

2.2.1. Part - 1. 2

3.       Chapter - 1. 2

3.1.    Section - 1. 2

3.1.1. Part - 1. 2

3.1.2. Part - 2. 2

4.       Chapter - 1. 3

4.1.    Section - 1. 3

4.2.    Section - 2. 3

4.2.1. Part - 1. 3