I can do this by specifying both cases for each character in each entry:
[Bb][Ii][Nn]
*.[Tt][Mm][Pp]
Is there a simpler way to turn the whole list case insensitive?
The linked question (Can I make Subversion + TortoiseSVN case-insensitive for Windows?) is similar indeed, but it is about ignoring a case change in a source file name. That is not possible while creating a case insensitive ignore list clearly is (see the above example). It looks like there's no easy way though.