i have done this in a quick and dirty way...

first i downloaded some free outline fonts
the one i chose is "ReSiple". "Sci Fied Outline" may also look good.
i copied the font to /usr/share/fonts/


then modified "/usr/share/themes/base/meegotouch/libsysuid-screenlock-nokia/style/libsysuid-screenlock-nokia.css"

LockScreen MLabelStyle#LockScreenLowPowerModeClockLabel {
font: $FONT_FAMILY_"ReSiple" 10mm;
...

after that i modified the most common icons that appear on the low power standby screen:
/usr/share/themes/blanco/meegotouch/icons/

icon-m-low-power-mode-email.png, icon-m-low-power-mode-missed-call.png, sms, chat ...

in gimp i selected the white inside with the magicwand tool. then i reduced the boarder by 1-2px and removed the left selection with "Del".

someone should redesign the icons with more time to make them look better. i think the problem is, that the lines are too thin and the oled displays only one of the subpixels..