Hey pluckyduck,
the reason, that you can't figure out how to exclude/include users with "cifs shares -add" is that you cannot do it in one step.
First you have to create the share: cifs shares -add share1 /vol/vol1
Second, remove everyone/fullC. : cifs access -delete share1 everyone
And the last one: cifs access share1 -g domain1\|group1 "Full Control"