It's supported in the Switch CLI:
switch(config-pa-role)# vlan access
<1-4094> VLAN identifier.
name configure the VLAN name.
You'll need to use the "advanced" option when creating the Enforcement Profile and enter the role via commands rather than the Standard UI. We're looking into getting that updated in ClearPass.
Make sure you're running the latest CX build - 10.05.0001+