I would think that "ImportPart" would work. So you could pre-create your arrow, then have a script call it with importpart and you could use it as needed.

Try this arrow. Then in MoI, hit tab and type ImportPart. Navigate to this file and test it... Of course, this has you navigate and select the 3dm arrow file, but I think a script could hard code the file so just the shortcut would produce the arrow to orient and place. There is also "PastePart" which will provide the orient and place, if you have it on the clipboard already.

I had no idea the extra copy and paste functions existed, and are so powerful!
I understand the method your proposing, however the (CTRL+SHIFT+V)orient and place tool does not take care of variable-length pointer lines.

While thinking about it further I did come up with a work around - using the "line/line" orient tool: Starting with your idea of having a predefined pointer(moved to one side for now) I activate the tool(with options set to: "copy" and stretch") and follow the usual procedure. Stretch ensures the arrow is minimally changed and copy means I can draw many pointer lines after a single selection.
The next improvement will be to find how to pre-load the pointer object automatically, and the start and end points pre-selected for the "line/line" orient tool.

Thanks,
Ambimind

The line/line use was pretty cool, although it does morph your arrow, so you would end up with all different shapes... I think this may be just something we need to wait for the basic annotation tools Michael will be adding....