Convert office documents to PDF with LibreOffice
See newer version here: Convert Office Files in FileMaker

You can learn about command line commands in the help: Starting the LibreOffice Software With Parameters.
To show an example, let us convert a Word file to PDF:
/Applications/LibreOffice.app/Contents/MacOS/soffice --convert-to pdf --outdir /Users/cs/Desktop /Users/cs/Documents/test.doc
To run this, you can use Shell class in Xojo or Shell functions for FileMaker in MBS Plugin.
In FileMaker, you can run this with shell functions like this:
Set Variable [ $shell ; Value: MBS( "Shell.New" ) ]
Set Variable [ $s ; Value: MBS( "Shell.Execute"; $shell; "/Applications/LibreOffice.app/Contents/MacOS/soffice"; "--convert-to"; "pdf"; "--outdir"; "/Users/cs/Desktop"; "/Users/cs/Documents/test.doc" ) ]
If [ MBS("IsError") ]
Show Custom Dialog [ "Failed to run" ; $s ]
Else
Set Variable [ $s ; Value: MBS( "Shell.Wait"; $shell; 10) ]
Set Variable [ $error ; Value: MBS( "Shell.ReadErrorText"; $shell; "UTF-8") ]
Set Variable [ $result ; Value: MBS( "Shell.ReadOutputText"; $shell; "UTF-8") ]
Show Custom Dialog [ "Converted" ; $result & ΒΆ & $error ]
End If
Set Variable [ $r ; Value: MBS("Shell.Release"; $shell) ]
Enjoy conversion!