Using iPhone Backup Extractor, I copied my iPhone's
~/Library/Application Support/iPhone Simulator/6.0/Library/Keychains, overwriting the existing file. I tried to only insert a single row with the following sqlite, but I couldn't get it working.
sqlite3 ~/backup/iOS\ Files/TrustStore.sqlite3
sqlite3>select * from tsettings;
working.sql has the entire contents of the tsettings table (in my case, 1 row).
sqlite3 ~/Library/Application\ Support/iPhone\ Simulator/6.0/Library/Keychains/TrustStore.sqlite3
sqlite3>INSERT INTO tsettings VALUES(X'...
Again, the above sqlite commands didn't work for me, but might be a good starting point for someone else. Copying the entire
TrustStore.sqlite3 from the backup into the simulator worked just fine.