I have noticed a peculiar thing about Outline Labels when running under eccoext: they seem to be limited to 3 cumulative levels.  
 
For example, if I double click on a .eco file and run it under the "old" ecco32.exe I can have up to 9 cumulative levels of labels e.g. 1.1.1.1.1.1.1.1.1 but if I open the same file under eccoext.exe I can only get 3 cumulative levels e.g. 1.1.1.  
 
This applies regardless of what level I start the numbering at, or what kind of numbers (1 2 3, A B C, a b c, i ii iii, etc). I can still get non-cumulative numbering at all levels but it looks peculiar to get:  
 
2
  2.1
     2.1.1
     2.1.2
           2.1.2 (not 2.1.2.1)
                 2.1.2 (not 2.1.2.2.1)
 
Looks like a bug in eccoext to me. My solution: just open the .eco file by double clicking. This opens it with ecco32.exe and the levels can be seen. OK for printing but not really satisfactory.