You can't do that without changing the
DrawMode
Property to
DrawMode.OwnerDrawFixed<br />
but that will remove some functionality, you then have to add all items programatically by your own.
Here i googled a C# sample;
Make an owner-drawn ListBox in C# - C# HelperC# Helper
I have made such a ComboBox control in VB.NET with many extended features like; BorderColor, DisplayText, ItemsForeColor, ItemsBackColor, ItemsFont etc..
If you want it i can send it to your Email, it's in VB.NET.
Please accept this answer if it helped you.