Read and write to customized attributes

Hi,
    
I add new custom attribute type 'Tag' When I manage it through the GUI it is working great (every tag window, have it own value)

RTC version is 4.0.4

I'm trying to write some code to add it by programmatically, I run over a query, and then I enter every WI.
The code the add Tag is : workItem.setTags2(List);

But I can't use this since my Tag attribute is customized.

So I try to use: iAttribute.getValueSet(auditableCommon, workItem, monitor);
This class return Object[];

"Object[] com.ibm.team.workitem.common.model.IAttribute.getValueSet (IAuditableCommon arg0, IWorkItem arg1, IProgressMonitor arg2) throws TeamRepositoryException"

I can't figure out how to use it, what is the Object should be casting by?
How can I read and write the customized attributes?

Thanks
Kunal