Apply a custom character style partly to a custom caption style using VBA

[andreas]

Hello:

I have got lots of tables and figures in a long document. All of these
captions are formatted with a custom caption style. Now I would like to
be able to apply a custom character style (custom_char_style_bold) to
only part of the table and figure captions.

For example:
Table 1-1: Comparison between ...
Figure 2-2: Bar Chart showing ...

Now only the characters till the colon (including the colon) should be
formatted bold by applying this custom character style
(custom_char_style_bold). The caption text itself ("Comparison between
....."; "Bar Chart showing...") should not be affected.

How can I achieve this using VBA. Any idea ? Help is appreciated.
Thank you very much in advance.