Indexing big TAR files is very slow. It is not useful.
Now you can convert you TAR files to sqlitedb format. The sqlitedb files dont need indexing on the android devices.
Use gmv2sqlite for it http://code.google.com/p/robertprojects/downloads/list
Unpak files from the tar file (for example to c:\temp\). Use PeaZip for example.
Write in console: gmv2sqlite.exe c:\temp\
The program will generate c:\temp\rmaps.sqlitedb file