Some months ago I wrote a post about how to activate SSH on a ESXi 4.1 via console. But you can also activate SSH with the vSphere Client.

1. Login to the vSphere Client
2. Click on the configuration tab
   
3. Click on Security profile
4. Click on Properties
   
5. Click on Remote Tech Support (SSH)
   
6. Click on Options and choose the startup policy and click start
   
7. Now you can verify that the daemon shows as running in the Services Properties window