Here's a possible approach to finding sector numbers for secrets:
- Fire up SLADE, load the Doom 64 WAD, open MAP34 in the directory, double-click the MAP34 marker, in the Launch pop-up select Game: Doom 64, view the map in sectors mode ('S' key).
- In the game go to each secret and look on the automap where you are, then find that same place in SLADE and hover the mouse over it to see the sector number.
- Enter the description to reach that secret at the bullet with the matching number. Re-ordering the list in the order the secrets are encountered during play is encouraged.