It depends upon which kind of .pyc file you are trying to edit. I assume, here, you are trying to edit a ship hardpoint (that is, the file which detemines its weapons, shields, etc.) which are in the scripts\ships\hardpoints folder. As mentioned above, .pyc files are close to uneditable; unless you have the Model Property Editor in the Bridge Commander SDK.
To start editing a ship with the MPE, you must first load a .nif ship model (found in data\models\ships\[ship name]\, then it will ask you to load your hardpoint, so you need to find your .pyc hardpoint and select it. To view the attached hardpoints, you must check the 'Named Objects' box on the right-hand side of the screen (when you can see the ship model in the viewer), and then click on the 'Scene Root' option in the menu above. From here, you can edit any of the hardpoints from the menu on the left-hand side of the screen.
However, MPE can be difficult to use (I still find it annoying at times), so if you just want to edit the settings without adding any new ones, I would just hit the save button as soon as you load the hardpoint in MPE - which will save it as an editable .py file. From here, I would use the far simpler 'Hardpoint Tweaker' feature in BCUT (available from BC Files) to change a ship's settings. Hope this helps ;) .
Edit: Just noticed you mentioned you use KM1.0, there should be a folder named 'src' in the BC directory, which contains copies of all the .py files from the KM install. But if the one you need isn't there, just use the method above.
