Custom Property for Remove Duplicates transform Input Row

Im working through the MS example of "removeDuplicates". I cant seem to figure out how to add custom property for input column.

I added the helper method:
private static void AddIsKeyCustomPropertyToInput(IDTSInput90 input, object value)
{
IDTSCustomProperty90 isKey = input.CustomPropertyCollection.New();
isKey.Name = "IsKey";
isKey.Value = value;
}
I call it from:
public override void ProvideComponentProperties()
{
//...
AddIsKeyCustomPropertyToInput(input, false);
//...
}
public override void ReinitializeMetaData()
{
IDTSInput90 input = ComponentMetaData.InputCollection[0];
if (input.CustomPropertyCollection.Count == 0)
{
AddIsKeyCustomPropertyToInput(input, false);
}
// ...
}

However when I deployed it and added the component to SSIS package - I cant see the Custom Column "IsKey" in the input column properties window.
What am I missing - please help As stated by some fore-sightful guy in a blog -

the way to SSIS enlightment is treacherous

. it seems i was missing something very basic - i was trying to set custom property for the whole input instead of just input column.

So instead of 2 above mentioned calls (in ProvideComponentProperties and ReinitializeMetaData ) i needed to set it in following:

public override IDTSInputColumn90 SetUsageType(int inputID, IDTSVirtualInput90 virtualInput, int lineageID, DTSUsageType usageType)
{
if (virtualInput == null)
{
throw new ArgumentNullException("virtualInput");
}

IDTSVirtualInputColumn90 vCol = virtualInput.VirtualInputColumnCollection.GetVirtualInputColumnByLineageID(lineageID);
IDTSInputColumn90 col = null;

/// No support for BLOB image columns.
if (vCol.DataType == DataType.DT_IMAGE)
throw new Exception("Binary data types not supported.");

/// If the usageType is UT_IGNORED, then the column is being removed.
/// So remove it from the outputs also.
if (usageType == DTSUsageType.UT_IGNORED)
{
/// ...
}
else
{
/// Let the base class add the input column.
col = base.SetUsageType(inputID, virtualInput, lineageID, usageType);
// Store the lineageID of the input column in a custom property of the output column.
IDTSCustomProperty90 inputColIsKey = col.CustomPropertyCollection.New();
inputColIsKey.Name = "IsKey";
inputColIsKey.Value = false;

/// Add an output column to the distinct and duplicate outputs.
AddOutputColumn(ComponentMetaData.OutputCollection[0].ID, col);
AddOutputColumn(ComponentMetaData.OutputCollection[1].ID, col);
}
return col;
}

Hopefully - when i have created this transform to filter duplicates based on (Primery) Key column(s) i can post it in my blog (to be created)|||Now if only I could figure out how to pass this custom "IsKey" property to class "Row" Equals operator and to class "Buffer" sort method