Based upon my limited information (since numerous changes have been made to both engines):
5S-FE (D-type EFI as used in the autoshop101 manual on EFI) uses a MAP (manifold absolute pressure) sensor and the 3S-FE does not.
3S-FE (L-type EFI) uses an vane-type AFM (air flow meter) and cold start injector, and the 5S-FE does not.
Neither one uses a wire-type MAF (mass air flow) meter
For general desciptions of the various systems involved see:
http://www.autoshop101.com/forms/h20.pdf
http://www.autoshop101.com/forms/h21.pdf
http://www.autoshop101.com/forms/h22.pdf
http://www.autoshop101.com/forms/h34.pdf
http://www.autoshop101.com/forms/h35.pdf
and others at
http://www.autoshop101.com/
Particular information related to the 5S-FE:
Here's a link to a wiring schematic for a 1994 Camry which should be quite close to yours:
http://www.turboninjas.com/camry/camry94wiring.pdf
Here's a link to a harness repair manual:
http://www.turboninjas.com/camry/Harness_Repair.pdf
Here is the general link to repair manuals for 1994 Camry:
http://www.turboninjas.com/camry/
Particularly see page EG1-164 and so on in:
http://www.turboninjas.com/camry/eg1.pdf
(All of the above links are in the sticky post at the top of this forum)
It appears that your best approach would be to duplicate the 5S-FE as exactly as possible using the above information as a guide, seeing how you are forced to use a 5S-FE ECM. Maybe someone with further experience will post and guide you more precisely.