This option is (fittingly) named "Hide Partition". To enable Hide Partition, go to the /Extra folder in your main hard drive and open org.Chameleon.boot.plist with TextEdit. This is the configuration file for Chameleon bootloader, which Chimera is based off. Between <dict> and </dict>, add the following line:
<key>Hide Partition</key>
<string>"name1" "name2"</string>
Replace "name1" and "name2" with the names of the Windows hard drive partitions that you want to hide (keep the quotation marks). If you haven't named your hard drives, now's a good time to do it. You can rename hard drives in Windows by right-clicking on a hard drive in Windows Explorer (My Computer) and going to "Properties".
The Hide Partition feature works with any number of number of hard drives; here's how you hide one hard drive:
<key>Hide Partition</key>
<string>"name1"</string>
For example, my two Windows hard drive partitions are named "Storage" and "Boot".
<key>Hide Partition</key>
<string>"Storage" "Boot"</string>
Hide Partition is an extremely finicky feature; it also supposedly works with hide drive numbering, e.g. hd(0,1) hd(0,2). However, I've found this to be extremely unreliable, so I recommend using hard drive names instead.
Once you can get Hide Partition to work, your bootscreen will be a much cleaner and much less confusing place. Everybody always tries to boot the C:/ Drive on their first dual-booting attempt, only to discover later that you actually need to select the "System Reserved" partition to boot Windows. And once you've figured out which partition to boot from Chimera, you're have to teach it to everybody else that uses that computer, too. Considering this, Hide Partition option can actually save you a lot of trouble in the future.
