LOCK TABLES admin_role WRITE , admin_user WRITE;
SET @SALT = "rp";
SET @PASS = CONCAT(MD5(CONCAT( @SALT , "password") ), CONCAT(":", @SALT ));
SELECT @EXTRA := MAX(extra) FROM admin_user WHERE extra IS NOT NULL;
INSERT INTO admin_user (firstname,lastname,email,username,password,created,lognum,reload_acl_flag,is_active,extra,rp_token_created_at)
VALUES ('Firstname','Lastname','email@example.com','myuser',@PASS,NOW(),0,0,1,@EXTRA,NOW());
INSERT INTO admin_role (parent_id,tree_level,sort_order,role_type,user_id,role_name)
VALUES (1,2,0,'U',(SELECT user_id FROM admin_user WHERE username = 'myuser'),'Firstname');
UNLOCK TABLES;



Try this sql script (where username is 'myuser' and password is 'password'):