Check out Josh Kurlantzick's new book Charm Offensive for a good read on China's use of diplomacy, trade incentives, cultural exchange, and various assistance packages to change its image and win friends in Africa and elsewhere.

Not that published policy and actual policy match, but if you haven't seen China's 2006 Africa Policy, it's worth skimming. The policy is in six parts:
1. Africa's Position and Role
2. China's Relations with Africa
3. China's African Policy
4. Enhancing All-round Cooperation Between China and Africa
5. Forum on China-Africa Cooperation And Its Follow-up Actions
6. China's Relations with African Regional Organizations

Also noteworthy is China's intentional use of peacekeeping missions to up regional and global profile.