Ashish,
Yes, you can run both 3.8.5 and 4.0.x on the same machine, you just have to ensure you are using separate Eclipse instances for them. MyEclipse 4.0.x requires Eclipse 3.1.x so the best thing to do is simply download and install a new Eclipse 3.1.1 distribution. Once that’s done, download an install a copy of MyEclipse 4.0.2 so that it points to the 3.1.1 install. At that point you can then run either MyEclipse 3.8.5, using your existing installation, or 4.0.2 using the new one.
is there any document to migrate projects from 3.8.5 to 4.0
No migration is necessary as the projects in 4.0 are backward compatible. However, to test I’d still recommend that you use a copy of your 3.8.5 workspace just to be absolutely sure you don’t run into any sorts of issues. Once you’re done testing, you can simply open your original workspace with 4.0.2 and continue development.
does 4.0 support myfaces 1.1.0
4.0.2 includes MyFaces 1.0.9. We plan an upgraded on to the latest MyFaces release for our next MyEclipse release.