Like most IDE's nowadays you can change settings via XML files, CFEclipse is no different. I've just added insight for the ERROR structure to the dictionary for build 1.1.16. To do this goto:
{eclipse}/plugins/com.rohanclan.cfml.xxx/dictionary.Open up cfml.xml, scroll to the bottom and add your code. You can look through the file to see how to set up your insight. To see it in action hit CTRL+F5 to reload the workspace.Below is the code i've just added to the dictionary.

<!-- ERROR scope variables -->
<scope value="ERROR.BROWSER"/>
<scope value="ERROR.DATETIME"/>
<scope value="ERROR.DIAGNOSTICS"/>
<scope value="ERROR.HTTPREFERER"/>
<scope value="ERROR.INVALIDFIELDS"/>
<scope value="ERROR.MAILTO"/>
<scope value="ERROR.QUERYSTING"/>
<scope value="ERROR.REMOTEADDRESS"/>
<scope value="ERROR.VALIDATIONFOOTER"/>
<scope value="ERROR.VALIDATIONHEADER"/>
<scope value="ERROR.TEMPLATE"/>

Thanks to Spike pointing me in the right direction