I'm using KDE4, which uses LightDM for the login screen on Kubuntu. There's no options to enable one from the KDE System Settings. Due to issues with my video card, I sometimes have to restart my x-server. When I do this, my keyboard becomes disabled till I log in (from gnome15 drivers for my logitech keyboard), causing me to have to plug in another nearby keyboard, or reboot and allow auto-login to take me to desktop, since auto-login doesn't work when you restart X.

How can I setup an on screen keyboard to allow me to virtually type in my password?

I'm quite surprised I found no useful results on google for this question as I don't think it's an unusual feature.

Is this a touchscreen?
https://wiki.ubuntu.com/Touchscreen

No, it's a desktop system that has the keyboard disabled at login if I restart X as described in first post.

With newer versions of lightdm (1.5.1?) there is a commented out line in thelightdm-gtk-greeter.conf file. The option at login is shown if you insertkeyboard=whatever_to_start.

Example for onboard:

[greeter] keyboard=onboard

see patch:https://bugs.launchpad.net/lightdm-gtk-greeter/+bug/905809