When CyanogenMod 9.0 stable was released a couple of weeks ago, the list of supported devices was dominated by Samsung and Sony Ericsson phones. Fortunately, the team has been hard at work since then to bring the popular firmware to as many devices as possible, and HTC EVO 3D owners will be glad to know that they can download a nightly build of CM 9 right now.
The build is currently available only for GSM models of the device, with CDMA remaining unsupported at the moment. Hopefully, as development progresses a little more, it will become available for both varieties of the phone.
It could oftentimes be unstable and not properly tested, lacking any changelogs, but eventually evolving into alphas, betas, release candidates, and finally stable releases.
Nightly builds of CyanogenMod 10 began just a couple of days ago, so it might be a while until the EVO 3D is supported by the very latest firmware, but there's no reason why it shouldn't receive the update at some point in the future.
If you want to try out Cyanogen on your EVO 3D, you can download the latest build from the CyanogenMod Downloads website. This is a bleeding edge release, so be aware that there will probably be quite a few bugs throughout. As always, make sure that you back up your phone before flashing the new ROM.
Source: Cyanogen Downloads