Here are some rules ...

You can use any legally purchased books. You cannot use illegal copies.
You may copy "a part" of a publication for in-class teaching purposes (e.g. a page), but be very careful because copyright law differs depending on country.
You may not copy any part of CD recorded material.
Not only the publishers will have a right but also ETS.org therefore you need to follow the copyright guidelines of ETS® on any material you create yourself that includes any ETS IP (e.g. logos). You should be able to get the rules using Google®, if not, contact ETS.org in your country.

There are also preparation training platforms for the TOEIC® test online which can also be used in class. One example is OnlineEnglish Preparation for the TOEIC Test (http://www.onlineenglish.eu). This website is operated by an official TOEIC test center, ETS EPV and qualified language teachers. It includes both preparation material and traditional English language exercises. They follow the ETS copyright guidelines exactly.
Be careful with other websites and make sure that they follow the guidelines, otherwise you could get into trouble copying pages from the platform/website and distributing them in class.

Preparation material for the TOEIC test is a very big marketplace, therefore whatever materials you decide to use, be very careful as much of the advice given can hinder and not help students sitting the test. Best always to use material produced by ETS or organizations such as EPV's, Test Centers ... etc that know and understand the test.
As a teacher wishing to prepare students for the TOEIC test, make sure you learn about the test, preferably sit the test yourself. Many organizations and teachers prepare students for the TOEIC test, but really although very good teachers, they have limited ability when preparing a student for the test.
Remember that preparation for a test is not learning English, therefore you should be prepared to give additional English language training to your students. Don't rely on asimilated learning alone.

In summary, as a teacher it is always better to stay away from free material. It is better to get preparation material from official sources. If you produce documentation in support of your course or class, then make sure you follow the ETS guidelines; this also includes any marketing material or indeed any content on your website. Be aware that copyright law is different in each country (e.g. France) even though treaties may exist, therefore be careful when researching copyright law on the internet. Best follow the guidelines of the IP owner.

I think that's about all. Follow my guidelines and you should be ok.

Rob.
Authorized TOEIC test administrator.
www.hamburg-english.eu
Official TOEIC Test Center.