Here's how I got the Orca 2.91.5 stable sources and built them.  

Before downloading or building anything, make sure you've installed build-essential, python-yaml, and the build dependencies for Orca.  

In a terminal or console, do:

sudo apt-get update
sudo apt-get install build-essential
sudo apt-get install python-yaml
sudo apt-get build-dep gnome-orca

to connect to the gnome ftp server, I used nautilus.  It works well, and should be familiar.

To connect Start nautilus with  'menus->places->home folder', or use a hot key.

I opened a new window with 'ctrl+n'.
To reach the ftp server, I used 'file->connect to server'; use 'alt+f' to pull the menu down.
In the dialogue that appears, make sure that the combo box has the 'public ftp server' option selected.
Tab into the edit box, labeled 'server', and enter 'ftp.gnome.org', (without the quotes).
Tab past the 'port' box, into the 'folder' box, and type '/pub'.
Tab four times, to the 'connect' button, and hit 'space'.
You should see a new file browser entitled 'pub'.  Wait a while, for it to get populated.
Look for the 'gnome' folder, and enter it.  Again, wait for the list to get built.
Select the 'sources' folder.  You can type this word, and hit 'enter', if you like.  If the title now reads 'sources', you're in the right place.
Since there are tons of items, here, I typed 'orca', and selected the folder.
Navigate to the '2.91' folder, and enter it.
I moved to the 'orca2.91.6.tar.gz' file, and hit 'ctrl-c', to copy selection to clipboard.
Use 'alt-tab', as many times as necessary, to switch to your nautilus window on your home folder.
Use 'ctrl-v', to paste the file into your home folder.  This may take a while, and is dependent on the speed of your connection.  The progress bar updates will tell you when it's finished.
When you have the file, close your nautilus windows.

Now, go to a console or gnome terminal window.
It's time to open the tarball.  To minimize typing, and thus, the chance of error, I typed:
'tar -zxf orca', and hit tab, letting the shell complete the file name.  If you have one file with name beginning with 'orca', in your home folder, you'll hear the terminal fill in the rest of the characters.  Hit 'enter'.  The decompression of the archive should be very quick, and you will return to your shell prompt.

Enter the resulting directory with 

'cd orca', press tab and enter.  The name should complete as before.

Time to build!

type './configure --prefix=/usr', and hit enter.
You may want to silence speech, until hard drive activity stops.
Review your screen for errors.
Now, type 'make', and hit enter.  Again, you may want to silence your synthesizer, until the compiling is done.  This command spews output.
Again, look for errors.  If the last lines before the shell prompt say things about completed translations, the build very likely went correctly.

We have a build, but orca is not yet installed.  Next, I typed
'sudo apt-get remove gnome-orca'.
To install your newly-built orca, type
'sudo make install'.

You're done!  If you did this work in a gnome terminal, close and restart orca.

To close Orca: do: Insert+Q: then enter.
To restart Orca: do: control+alt+o.

When the new orca starts, it will make you go through the preferences dialogue again.  Just set everything up as you like it, and enjoy the improved responsiveness of the new orca.