Allready done a while ago. 
I personally think this post/howto should be made unnecessary by adding that simple line by default to the lightdm greeter. It's really stupidly simple. 
As I mentioned in the comment there:
yes but only if a touchscreen is detected 
hum, so you suggest "in case that no keyboard is detected" ? that makes sense...
No, I'm suggesting to put it there by default.
Now the installer will include the "Size:" value too on this disk (partition size), this feature is not tested so the next time you upgrade your elive with multiple elive's found, make sure (betatest) that it works 
having a visual keyboard to appear in everybody's computer that is not needed its just annoying and an UX issue, by other side:
the only issue now is that computers without keyboard has probably some keyboard emulation hardware detected as a keyboard, for example, in a WeTab device where I tested the feature it simply not worked because there's a "touch" button in the corner which acts as a 2-keys keyboard, by hardware, its simply detected as a keyboard device
in other words, it can improve the user experience in the cases that the hardware has really not a keyboard detected, and on this specific case, if the comptuer is a WeTab, it is whitelisted to be enabled by default too (any other hardware recommended to apply, @triantares?)
I wasn't advocating the un-asked appearance of a virtual keyboard. 
What I am advocating is the option to acquire one in the lightdm login screen using "only" touch features i.e through the top right menu or even an icon that opens a keyboard.
That way there's even a fall back in those cases when the existing keyboard isn't there, for instance because USB doesn't work on a wake up from hibernation etc.
Of course this only is needed if one has not opted for autologin.
In my (and my daughters) case, using the helix2 ..... if I don't have my keyboard along I'm in trouble as there is no way to login on boot up....unless I've added those lines to lightdm-greeter.
IMO trying a list of known tablet[hybrids] is asking for trouble as there will be many more, in time.
exactly
i have tried to include an autodetection but this is is not posible if the device itself has some hardware identified as a keyboard device (like the WeTab which I tested)
@triantares I just tried the "keyboard=onboard" on lightdm vbox, it doesn't appears by default (which is what i think you meant) but after to select it from the accessibility menu, is that what you have been suggesting? I wonder if enabling this adds more resources usage (seems like no if is not run by default)
funny thing: when you select the option there's the F3 hotkey to enable it, so, press F3 key if you don't have keyboard 
note that the feature that I implemented also ran the virtual keyboard on the E desktop itself (but again, only if there's no keyboard hardwares detected, so I assume that it can solve -some- problems of the users)
Exactly.
That way it will also be accessible for those that lose a keyboard through other reasons ..... like spilling coffee or such.
Which isn't really necessary as "onboard" can be accessed through the application menus.
Now to see if we can get in "entrance" too.
ok, i will enable onboard for all installs by default for lightdm
that's a feature to implement, there's already a "bug report" on the entrance fork about that, but let's see how much entrance can work as a stable option first (no desktop crashes, correct steps procedures like logout, relogin, etc), autologin feature working too? (needed), etc
note that also lightdm has features that entrance may not have (like switching between users, this feature is already implemented in elive from the elive / users menus) or remote desktop login (nobody uses that in fact, but is a good feature), etc, we need to know that entrance is a good login-manager candidate to use
Do you have an own fork for Elive on github or is it now part of Enlightenment E23 and should the bugs be reported there?
