rgr, I was responding to your question about how to actuate VVI above.
For the levers, we have the following datarefs to reflect throttle lever angle when in autothrottle:
ixeg/733/engine/eng1_thro_angle / ixeg/733/engine/eng2_thro_angle
...FWIW, we also have for the reversers:
ixeg/733/engine/eng1_rev_angle / ixeg/733/engine/eng2_rev_angle
Regarding the default 737...as one who used to work for Laminar developing aircraft, they keep their customization to a minimum and develop their models to use the default datarefs. If some significant functionality were to be missing...we'd just go tell Austin and he'd customize stuff and give us new datarefs....but now that I'm "on the outside", we don't quite have that luxury and so have to go custom and abandon default datarefs when they don't suite our purpose.
....and finally, the dataref for the VS annunciator is:
ixeg/733/MCP/mcp_vs_dial_ann
Hope this helps.
-TomK