Realtime one-way mirroring of a SQLite database

I am dealing with a 3rd party application that's running a SQLite 3 database with WAL (Write-Ahead Logging) on a local computer, and I'm looking to mirror that database (read only, this is a one-way mirroring) to another system. The challenge is that I'm running in a separate process, which seems to complicate things somewhat.

The database is being created and opened with a normal locking mode so there's no problem reading it from another process, but I'm trying to either find an existing implementation or get some pointers on where to get started. My understanding, based on other posts is that the standard sqlite update hooks (such as sqlite3_update_hook) will not work out of process.

A key issue is speed, I'd like to ideally be able to detect each update as soon as it happens and begin transmitting it. This means that most polling options would be out of the question, but even if they were, how would you detect the most recent changes?

I'm seeing two files that look promising: the actual WAL file (foo.db-wal), and that memory mapped index file (foo.db-shm). I'm hoping that those two contain the information I need to: A. Detect when changes occur in the database and B. Be able to grab just the incremental changes since the last update.

But a pointer to some existing solution would be much preferred... :-)