Rob,
R14 and above have the option, under schedule tags, to pick a tag with a leader attached. These tags are AEC multi view blocks and they get attached to objects using property set definition. Property Set Definitions allows you to include information on the object and export the info into a schedule.
To create a custom Tag you must set up a property set definition, then create the block (tag/bubble&leader), then create a multi view block (AEC object), and then create an AEC object link to the tag. This is an example of the string to included in the link.
_AecAnnoScheduleTagAdd PropertySetDefs.Dwg _SYMBOL Aec_Furniture_Tag _LEADER Straight _DIMSTYLE Aec_Leader_Dot_I
if you don't want to create a schedule out of such a tag, it may be better to use a lisp routine.