MDX Type In Parameter Values - not a picklist

Hi,

I know that this should be simple, but I just can't seem to get it to work.

I have a multi value parameter (model) for a SSRS report that feeds into a cascading parameter (make).

I was able to develop MDX queries to populate the drop downs for each of the parameters & it worked beautifully in Visual Studio. However, when it was pushed to SharePoint, the performance tanked. To make a long story short, I need to be able to have users type in the values they need rather than select them from a drop down. For example,

Model MDX Unique Name
Green [Model].&[73524]
Yellow [Model].&[87252]
Purple [Model].&[92115]

The MDX query I've been using has been:

WITH

member [pValue] as [Model].[Model].CURRENTMEMBER.UNIQUENAME

SELECT
{
[pValue]

} ON COLUMNS,


NonEmpty( [Model].[Model].[Model],
( StrToSet(@ModelName, CONSTRAINED)))

ON ROWS

FROM [Cube]

How can I change it so that the user can enter Green, Yellow, or Purple (Member_Caption) and have it return the UniqueNames which will feed into the cascading parameter?

Any suggestions anyone may have are most welcome.

Thanks,

Michele