HMR for 11 digits

Community,

I am looking for an help with element rule under From Header.

Requirement : To only match 11digit number in uri-user of From header and add "+" to make it E.164 number.

 element-rule

        name                  addPlus

        parameter-name

        type                  uri-user

        action                 replace

        match-val-type             any

        comparison-type             case-sensitive

        match-value               ([0-9]{11}$)

        new-value                $ORIGINAL+^"+"

I have done this with Store and manipulate method. But this time I want do that part of single element rule. How can I do that ?