Importing Altium ActiveBOM data into Innovator
Setting up the ActiveBOM
Set up the ActiveBOM as shown below. This is mostly the default configuration, but with the addition of one custom column called 'CE Number'

To create the custom column right click on the headers and 'Add custom column...'

Work through the BOM setting the appropriate Manufacturer and Supplier as the 'primary solution' until all parts are complete.
Work through the BOM and set the 'CE Number' column with any existing CE (or other AnTech) part numbers. Leave that column blank for any rows where a new part number will be required - this will be created automatically in the following process.
Once you are happy with the result, go to Reports menu > Bill of Materials

Check again that the correct columns are included as shown above, and set the following options in Properties > General:

Note: Currency doesn't matter here as the pricing isn't imported into Innovator.
Finally click 'Export' to generate the XLSX file.
Importing the BOM to Innovator and creating new part numbers
Open the part record for the PCA and click 'Edit'.
Go to the '...' menu and select 'Import Altium ActiveBOM xlsx':

Select the Excel file exported previously.
This will then import the data into the BOM creating new CE part records where there is no CE number included in the file.
This will also import the manufacturer and manufacturer part number information into the new CE parts.
Note: the manufacturer data in the Excel file for the parts with existing CE Numbers will not be imported.
Also note: At this stage the vendor part number information is not imported.
Review the imported data and finally click 'Save' on the part if you are happy. If not, delete the BOM items, edit the Excel data as needed and repeat the import process.
Note: the new CE Numbers are only generated once the Innovator Part is saved with its new BOM.
Importing Vendor details
The above step imports the BOM and creates any new parts with their corresponding manufacturer details, but it does not import the corresponding vendors and their part numbers.
This step is done for each vendor from the vendor record itself. Find each vendor in the Sourcing > Vendors section of Innovator:

Note: For this stage to work, the vendor names in the Excel file must match the vendor names in Innovator, or they will not be imported. If they don't match, manually edit the Excel file before completing this step.
Open the vendor and click 'Edit'. Then from the '...' menu select 'Import Vendor Parts from Altium ActiveBOM'

Again, select the same Excel file that you used in the BOM import step.
The program will then run through the Excel file matching each line with a vendor name matching the selected vendor and match them up with the manufacturer parts with the same part number. If there isn't a match, nothing will be imported.
On completion a blue information notification will inform you how many lines were successfully imported.
Check the entries in the vendor parts list and then click 'Done' to save and unclaim the vendor record. If anything unexpected happens then simply click the 'Discard' button, check your Excel file and repeat the process as needed.
Repeat this procedure for all the relevant vendors.