OIM App Server Session token certificate

Could you share the version of OneIM you are using?

The answer in general is yes, but the how-to donut depends on  it. 

version 8.0.1

version 8.0.1

You just need to change the thumbprint for the session certificate in the web.config of the application server.

  <connectionbehaviour>
    <!-- Session token certificate -->
    <add key="tokencertificatethumbprint" value="F18...." />
  </connectionbehaviour>

There is no limitation on the subject but you should follow your company policies for certificates in general. Keep in mind that this certificate is not used for encryption but for signing the sessions. The traffic via HTTPS is encrypted using the Web Server certificate from your IIS.