No it isn't possible to change the backcolor of a commandbutton, however there are alternatives to using a command button. Add a label and make it look like a button of your design, then assign the OnClick event as you would do a button.
Alternatively, use a picture and use the OnClick event of the picture object.
As I recall there is a database out there as freeware with a customised button library of over 800 buttons - here's the bad news I haven't found it yet and would like to know where it is???
Ian