Yes, this is possible. Rulesets can "import" other rulesets, then override settings for single or multiple rules. This can be configured from the Visual Studio UI using the steps described under "To create a custom rule set from multiple existing rule sets" at http://msdn.microsoft.com/en-us/library/dd264974.aspx (even if you only want to import a single ruleset). Alternately, this can be done by manually editing the ruleset file XML to add references to the imported ruleset(s). e.g.:
<Include Path="SomeOtherRuleset.ruleset" Action="Default" />
For an example of this, see the ExtendedCorrectnessRules.ruleset
file that was installed with Visual Studio.