I think there are two things here that should be addressed separately:
- Running Impala on non-CDH Hadoop. It is possible, though it is not tested or supported by Cloudera. However, other Hadoop distributions include Impala, e.g. MapR's distribution includes Cloudera Impala and Amazon announced support for Impala on Elastic MapReduce, and they have both tested that it works with their distributions. I assume you're not using MapR, either, but my point is just that it is possible.
- Running Impala on Hadoop 2.2.0. This is also possible as the CDH5 beta 1 release includes Hadoop 2.2.0, so Impala versions 1.2 and higher should work. Please do make sure you use the latest version (1.2.3 as of now) because there are a number of important fixes in the last few minor dot releases.
So yeah, it's possible, though it probably won't be a smooth installation and there isn't a lot of help for this use case. Good luck!