Here is the simple instruction to enable Telnet on Windows 8.
Step 1: Click on control panel in Metro Start.
Step 2: Scroll down and click on More Settings,
Step 3: Select View by: Small Icons in top right corner and Open Programs and Features.
Step 4: Click on Turn Windows features on or off.
Step 5: Scroll down and find Telnet client.
Step 6: To enable Telnet, Select Telnet client and click OK.
Windows will start to install Telnet client, it take some few minutes. it doesn’t require any restart. Once installed, you can start to connect server using Telnet client.