You will have to create a custom enterprise text field from PWA Server
Settings>Enterprise Custom Field Definition
Create a task text field and leave the attribute as None so that it stays as
a free form text field. Also, you will need to enable the option "Roll
down, unless manually specified " for the assignment level.
Then you will be able to use this field in adding it to the My Assignments
view.
The macro you wrote will have to set this field value as apposed to the
local custom field you are currently using. To set an enterprise field in
vb macros you have to use Call
Task.SetField(FieldNameToFieldConstant("[EntCustFieldName here]", [your
value here])
http://www.eggheadcafe.com/software/aspnet/30815583/macro-to-close-out-projec.aspx
Jonathan