First, create the symbol. I believe you can only use lines or text (annotation, NOT Insert -> Curve -> Text). When finished creating the geometry, click File -> Utilities -> Symbol Fonts. This will bring up the Symbol Fonts dialog. Select Define Symbol. This will bring up the Symbol Font dialog.
Before we get too far along, I should point out that I prefer to add either a vertical or horizontal line that passes through the center of the geometry. The midpoint of this line should be at the center of what will eventually be the symbol. Do NOT add this line as part of the symbol when prompted, but rather, use it as the connecting points. Again, that's just how I prefer to do it so when I place the symbol, it will be placed by its center rather than a corner or something.
When ready, bring up the Symbol Font dialog (see above) and select Define Symbol. If you want to create a new .sbf file, then define it. If not, then add to the existing default .sbf file. Next, input the name of the symbol and use a factor of 1 to keep the symbol the same size and scale (watch the cue/status line for what is expected). You will next be prompted to define 2 connecting points. Use the reference line I mentioned above, if applicable. You can select the same 2 points (the midpoint of the symbol centerline if you wish). Next select all applicable geometry or text. If using the centerline method, DO NOT select it as part of the symbol. When finished selecting all the symbol geometry, click OK. If finished and you do not have more symbols to add to this .sbf file, click Cancel. If not finished adding symbols, then start over with Define Symbol.
When finished, open the Annotation Editor to the FULL Annotation Editor, not just the dialog bar. Click on the User-Defined Symbol tab then select the .sbf file you want to use from the left column. You should see all of your Symbol names in the right column. To use the symbol in the Annotation Editor, type <%SYMBOL NAME HERE>. You should now see your symbol in the display area of the Annotation Editor.
Hope this helps.
Tim Flater
Senior Designer
Enkei America, Inc.