First, go to Truss Prep, and click on the Gear Icon ⚙️:

You'll be prompted to upload a .zip of your data file. Here are the instructions:

In your computer or server that holds the Lacerte data, navigate to C:\Lacerte\25TAX (or whatever the CURRENT tax year is).

Then, right-click on the IDATA folder. In the Windows Menu, go down to "Compress to...", and select "ZIP File".

This may take a few minutes to zip for large files.

Upload the resulting ZIP file to Truss.

You can watch this loom for how to generate the .DAT files to import:

Drop the file into Truss when ready.