Yes,
!important; should override the template.css
Easiest way to override the css is to:
1. Download and learn to use FIREBUG (
Every webmaster should use this with Firefox)
2. Locate the css using firebug and copy and paste the relevant css you want to override, into the custom module.
If you don't use Firebug you may be there for hours trying to figure out what is what...
