Good call, Chris!
Christopher, if you already have the Rod in your equipment inventory, manually changing the mods field would be the best solution, though I believe it should be Item Type: Adventuring Gear, Spell DC +1, Spell Attack +1 for the Rod of the Pact Keeper.
I had forgotten that the mods property even existed, haha! For reference, here is an older list of available keywords for the mods property. I'm assuming these are all still supported, but haven't tested.
Chris said:
For the Rod of the Pact Keeper, I will drag/drop the Staff of Power from the compendium and then tune the mods from +2 to +1 (and remove the AC +2). It's got the mods for saving throws and such.
I think this is what you need in the mods row:
Item Type: Adventuring Gear, Saving Throws +1, Spell Attack +1