Looking at the board, the pads are fairly straightforward. Two speaker pads, two switch pads, positive and negative LED pads, and positive and negative battery pads.
For your LED, blue, green, and white dies won't need resistors, but red, red-orange, and amber will. SF doesn't list the foreword voltages of the dies (they're
Cree XQ-Es, and that info can be found online), but a 1Ω 2W resistor should be fine. Though if you don't want to worry about it go ahead and grab a pre wired LED unit. If you want an illuminated switch, you'll need something like the DynaOhm resistor TCSS sells.
The one thing I am unsure about is how the speaker ratings for the board. SF is offering a 2W 8Ω speaker (similar to the TCSS premium) and a 4W 4Ω bass speaker, which is what comes with the ASP plug n' play kits. In the ASP kit, they wire a resistor to the speaker's connection to the board. So I don't know if that's only needed for the 4W speaker or not.
Hopefully SF releases a manual for the Sabercore boards, as well as listing the different die's foreword voltages so people don't have to hunt for it online.
Are you planning on adding a recharge port? If you are, you could always use a wired 3.7v 18650 battery pack from TCSS or Solo's Hold, unless you really want a removable battery.
But back to your question: If you have prior soldering experience, and watch some of the TCSS's YouTube tutorials and/or Shameem's SF Fallen install video, I think you could pull this off.