First, excuse me for being late in adding RAD Studio XE7 support in the Mercurial Integration project, but I would rather like to introduce a new project that will benefit other people using RAD Studio and Mercurial as well.
It is currently named just bds-mercurial-client and is intended to provide Delphi and C++Builder language bindings for the Mercurial command server soon so that you can write your own Mercurial frontend with RAD Studio. The code was just spun off from the Mercurial Integration code base and Mercurial Integration itself will also use it when it is ready for all targeted RAD Studio versions.
Please wait for the next update.