I too am in the same position! I have to support this billing system and have recently had an idx file go bad. I no longer have access to the programmer or source code of the system. I like to be able to download the data file off the motorola processor, rebuild the index, verify that all records are now accessible through the index, then upload the .dat and the .idx files and get back in step.
If anyone knows how to accomplish this (or has some sample C: or Java code ) I'd GREATLY appreciate it as well.
(I'm playing with some 'connectors' downloaded from IBM for java and C++ at the moment. If I come up with something, I'll post it here as well.)