How do we add metadata to IterationPlan?

Hi all,

we have a plan to extend IterationPlan,and we want to save metadata about the
IterationPlan.

Now we have 3 ideas.
- First,we add a workitem type to Process Template to do it programmatically.and custom attributes are added programmatically
>> we heard a license issue to do it.(Please see https://jazz.net/forums/viewtopic.php?t=2103 )
- Second, we use other attribute in IterationPlan, such as WikiPage.
>> But we don't want to rewrite our metadata by end users.
- Third, we use extension schema to do it.
>> Extension schema is too complication for us.

How should we do? Do you have any other ideas?

best regards,
-Hiroki Kondo