Access BOL attribute from component

I am trying to read the activity category from the web ui when creating a new activity. I do an F2 on the field and can see the following technical information

Component: BT126H_CALL

CN: BTACTIVITYH

Attribute: STRUCT.CATEGORY

From component GS_TEXT, which is a component usage of BT126H_CALL and on the same screen, I am trying to read this attribute. I have created context nodes in GS_TEXT for BTACTIVITYH but how can I bind this to BT126H_CALL so I can read the value? I've tried to code in WD_USAGE_INITIALIZE to bind the context node, but didn't seem to work.

Any help/suggestions would be appreciated.