Tested with IntelliJ 12.x / 13.x and Android Studio 0.3+. You can have others information about the plugin on jetbrains website.
Download the AndroidHoloColors.jar and put it in your IntelliJ / Android Studio plugin folder. See the documentation to know where it is.
Go to Preferences / Plugins and search Android Holo Colors :
If you can't see the plugin, you should either click on "Browse" (on the left) or "Install from disk" (the jar is available here):
Click on the Android Holo Colors icon (blue 'H') in the toolbar :
You should have the following screen :
Like on the website (http://android-holo-colors.com), you choose a name for your theme, you select the minSDKVersion, the compat library if necessary, and the widgets you need. You also need to specify where is your "res" folder. Finally, click "OK".
If some files were already present in your res folder (and subfolders), you have the following dialog to choose if you want to overwrite one file, or all files, or if on the contrary you don't want to overwrite one file, or no file :
You will also probably see the following screen. In this case, click on "Make a donation" or your computer will burn ;-)
Seriously, if you save time and money with Android Holo Colors, help me with a small donation :
Copyright 2013-2014 Jérôme Van Der Linden
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.