I don't think so, I tried playing with a css but the check stayed black.
You might want to make an image that looks like a checkbox with an onclick event to chage it to a checked box with your choice of colours, and put the actual textbox in a hidden layer, or just hide the checkbox with a style, and use javascript to check of the hidden checkbox so your code that processes the form will be able to get the value.
This will hide and with the javascript you can checkit off.
<input type="checkbox" style="visibility: hidden; clip: rect( )" name="checkbox" value="checkbox">