SPIP335 Line 2 as BLF Key

Hi,

Wondering if the second Line key on a SoundPoint IP335 can be used as a BLF key to watch hints generated on the PBX.

I don't mean watching another extension state with Polycom's built-in Presence and Buddy Watch feature.

I attempted to configure this key using a similar method as for configuring the same thing on the IP450;

<attendant
    attendant.reg="1"
    attendant.resourceList.2.address="*280"
    attendant.resourceList.2.label="Night Switch"
    attendant.resourceList.2.type="normal"
/>

Nothing displays on the screen against Line 2.

I haven't been able to find anything definitive but are BLF keys configurable like this on the IP335, running firmware UCS4.0.8?  Or, does this phone only support added a speed dial or Watched Buddy on this key?

Thanks in advance,