Get a copy of PICutil, dis-assemble them and see for yourself. That's how Keylog started life - a dis-assembled Secanix 5.
Also, now Threat has retired he has released all the source code for the different versions of Threat. Grab the source and have a gander. You will also be able to find the documented source code for Secanix 4.05g around and about (I think that's the version).