1. Change `IS_LEGACY_MODE` to `true` in `txBuilder.test.ts`
2. Download the latest dogecash version from https://download.dogecash.io
3. Unzip, rename the `bin` directory in it to `src`, and `dogecoind` to `bitcoind`
4. Within modules/ecash-lib, run `BUILD_DIR=<path/containing/that/src> npm run integration-tests`