I have RhoStudio 2.2 which looks to be built on top of Eclipse 3.7 (Indigo) and I tried to install the ADT plugin but was met with a error during install.
The work around I employed was Help > Install New Software
Click on Available Software Sites and add http://download.eclipse.org/eclipse/updates/3.7
Select Eclipse Platform and Platform SDK
Then Next follow to install
Once install you can install the ADT plugin and still have access to the Rho shortcuts. The main difference is when opening RhoStudio you'll have the generic Eclipse splash image.
Hope this helps for now.
Thanks this resolve the same issue for me on RhoStudio 4.0, but i lost the RMS splash and icon.
RMS is shipped as standalone IDE. We do not provide it in form of Eclipse plug-in and do not recommend to mix RMS with other platform specific plugins like ADT.
You need separate standalone installs of RMS and Eclipse with platform plugins