@veggie
If you want to use R10 but need that default changed, you might look at this :

https://unix.stackexchange.com/questions/42746/how-can-i-take-a-screenshot-in-lxde-using-scrot-and-the-print-screen-button-on-m   

It looks to me as if scrot config is in the file noted, so any change to add the "file location prompt" could be there too.   

If you are using microwatt, then you should got to the i3 FAQ.

This is vague recollection, since you don't seem to be making any usable progress.

Biff made a video for the first i3wm microwatt.   Updated it, I think, for R10.    I'm pretty sure that he covers - later stages, perhaps -  the fact that config is all in an editable text file.   I do realise that you want to allocate the MOD key itself given that none of the existing key functions that way, as opposed to binding mod+key combinations.   I say start with the video.   
Depending on your typing habits, consider a right-ctrl key as mod . 

Good luck - after this amount of effort you deserve it.   

..... or you could supply a cheatsheet      

And for the rest of us .....
  If the firewall is to work then it must be turned on. 
Everyone but Dan did that, right ?     Hmmmm, a big silence there.

Thanks for the reminder, Dan.   

IIRC (which isn't guaranteed)   HP provide a utility called  hplip  for installing printers under Linux.
I'd look in the repos for hplip, or try HP's website.     For an HP printer, that is.

I also support cheiron's comment .... sometime Samsung printers are a trivial install, but often a visit to the maker's website gets the best or only result.

MUCH better than my notes, Biff. 

UNchecking runtime-pm would, I assume, affect other devices too.  I speculate that it might improve network performance for some users, which would be a nice side effect.  Are there any negative consequences, potential or inevitable, which might push users to the more detailed solution .... among the weeds, as you put it ?    I'm guessing that printers, scanners and the like go to low-power at their own behest; what of HDDs and other internal devices ?  Or LAN polling, for that matter. 
Anything that might chew up enough cpu or power (whence heat) to become noticeable on a modest machine ?

Looked at another way, what benefit do those using a ps2 mouse or compliant usb meese get over  those who make this change out of necessity ?

Perhaps it's related to the usb-autosuspend feature of "laptop tools", in essence a power-saving feature.
You could find usb_autosuspend.conf (or something similar) and toggle that feature to off. 

If you want to retain power-saving generally, but address the usb mouse issue, then try this :
  http://www.hecticgeek.com/2012/06/fix-usb-mouse-not-working-laptop-mode-tools-ubuntu/ 
It's a vintage solution, so there's a chance the relevant config file has changed.  For example, in 
 http://askubuntu.com/questions/80638/how-to-disable-auto-power-off-of-usb-devices-like-usb-mouse   
one user noted "At least in Ubuntu 15.04, this file has been moved to runtime-pm.conf and the line to add the id to is now called AUTOSUSPEND_RUNTIME_DEVID_BLACKLIST="". Strangely, I couldn't get my blacklist to work so I just disabled this module by setting CONTROL_RUNTIME_AUTOSUSPEND=0. "

Or you could keep your hands clean and wait for Biff's notes    

For those new to wattOS, in earlier releases some issues on laptops were found to "magically" disappear when laptop-tools was installed, and not solely power issues IIRC.   So IMO electing to uninstall laptop-tools would represent a risky option.