Turns out that this is not so hard.
I wonder about syncing the Toolbar, the custom spelling dictionary and the user data between computers... That would be RMSpell.adu, RMSpell.ini, RMToolbar.ini, and RootsMagicUser.xml. But that might be more trouble than it's worth...
On the desktop:
1. I copied the folder C:\Users\Tom\AppData\Roaming\RootsMagic to Google Drive and renamed it "RootsMagic AppData".
2. I renamed the original folder "RootsMagic-original" so I could replace it with a symbolic link named the same as original.
3. Then, from the command prompt:
C:\Users\Tom>mklink /J "C:\Users\Tom\AppData\Roaming\RootsMagic" "C:\SD\Google Drive\RootsMagic AppData"
Make sure that the "RootsMagic AppData" folder is included in Google Drive's sync scope on both the desktop and the portable computer. The portable should soon have that folder.
Then repeat the steps above on the second computer except skip step 1 (or you will end up sending your portable settings to the desktop), assuming you have the same directory structure on both the desktop and the portable. If not, then you will have to change the mklink command parameters to suit.
I got this idea from http://www.dropboxwi...c-other-folders so it works with any of the synchronising utilities.
I don't know what the downsides may be - the upside is that my user toolbar and custom dictionary and other user things are now synced between my desktop and my portable, along with the database files. Just have to remember to Pause sync when working in RootsMagic and Resume sync when finished.
Edited by TomH, 06 April 2014 - 09:30 PM.