Registries have DACLs / CACLS (discretinoary access control lists / system access control lists ) just like normal files . You can add your username to the ACL of the registry key in question by following the procedure:
1.) open the remote registry with your registry editor (regedit should work on XP, but on some older versions of NT you may need to specify regedt32 to see the ACLs).
2.) Right-click on the hive / key in question and go to permissions
3.) Wala -- a familiar looking security dialog box should pop up. Add your username and specify permissions.
You should now be able to access said registry key.
 actually, all objects in NT managed by the ORM/Executive have ACLs.