Create VBScript to change Excel cell format

I need a way to change the formatting of certain cells of an Excel sheet. By formatting I mean both 'style' (such as Bold, Italic, Alignment etc) and data type (such as Text, Number etc).

The formatting will in some cases be applied to a range of cells or an entire column, in other cases it will be applied to a single cell only.

The VBScript will be generated dynamically and called from another application, so I will need to understand how it works...