Indu,
For after you get back from your "quasi disaster recovery mode...
First, I'm not certain what the definition of "custom formatting" is. But, I take it to mean a general term for changing the format of cells using "Format Cells".
Next, if you were to simply format a cell with a certain font, the ENTIRE contents of the cell will be formattted with that font.
However, if you want to want to mix fonts within the one cell, then the "key" (implicit) step is to be in "Edit" mode, so you can select those characters you want to change.
The mixing of fonts is also possible with "Text Boxes".
The advantage of utilizing the Wingdings Font is that one can have MUCH more flexibility in terms of the type of bullet - i.e. round, square, diamond, star, smiley face, mailbox, scissors, mouse, etc, etc.
To view a complete display of the fonts, one can enter all the letters (upper and lower case), plus numbers, plus other misc. characters on the keyboard, and then format this range of characters with the Wingdings font.
Some users might have other similar fonts, such as:
Zapf Dingbats BT, or Webdings, where there is a greater variety. A caution (recommendation) here, though, is that you preferably should stick to fonts that you can expect other users to have on their PCs - especially if you'll potentially be sharing your file(s) with others.
Finally, for anyone who might have missed it, another option was posted on the "sister posting" to this one (It was accidentally posted twice)... where the suggestion was to use <Alt> 0149 to produce a bullet. (Hold down the <Alt> key while you enter “0149” on the number pad). Naturally do this “ahead of the text” and while you are in “Edit Mode”. This type of bullet is plain and simple, but if that's all you need, then it's certainly a QUICK and useful option.
Hope this provides further help, and clarification.

(notice I'm STILL smiling)
Regards, ...Dale Watson dwatson@bsi.gov.mb.ca