There is no way to specify components when creating a snapshot. Please raise an enhancement request. Thanks.

One way of achieving this although a round about way is....
1) Create a workspace with --stream option... 'lscm create workspace --stream <stream> <ws>'
2) Remove the components that you do not need.. 'lscm workspace remove-component <ws> <comp>
3) Create the snapshot from the workspace
4) You can also associate this snapshot to the stream... 'lscm snapshot promote <stream> <ss>'
5) In 301, you could also delete the workspace... 'lscm workspace delete <ws>'

In Eclipse GUI, it is possible to create stream snapshot which contains a part of component. But it seems there is no option to specify components in CLI : scm create snapshot ?

Is there any good work around ?

Detail Step in GUI
----------------------
1. Click stream and create snapshot
2. Expand option, and then select components

=> This enable to create snapshot which only contains a part of components.

If there is no option, I'll raise as enhancement request (because CLI should support most of GUI operations).

I put the enhancement, which is interesting:
https://jazz.net/jazz/web/projects/Rational%20Team%20Concert#action=com.ibm.team.workitem.viewWorkItem&id=166075