If I was a good teacher, I'd get you on live chat and we'd go over your code together. But I'm lazy and making this myself was faster:
DateTimeLinearClock.py.txt

Just delete the ".txt" and put in the same folder as the other clocks. (/opt/maemo/usr/lib/advanced-clock-plugin/clocks/ - remember you have to be root to save there)

It's a mix of messy and okay code-wise. I left the copyright part as just Wonko's; I didn't change enough to bother adding my name.

If you look, all I did was change the text resizing values to those of the Digital Clock, commented out some of the lines, and edited one or two more, changing some variable names/order/position of things, etc.

You can delete the commented out lines without worrying about it (unless you want to add the year later). As is, it just doesn't show the year at all, and if you change it to twelve hour mode, the PM/AM appears after the date. The font size is pretty big by default, but that's what the scaling value is there for. If you want it much smaller, but want it centered instead of pinned down, just edit the 'move_to' line in the draw_clock section (and anywhere else they exist). Edit the second value, 35, to something smaller. For text, this determines where the bottom of the text is pinned to. 16±1 is about where the center of the box is. So ~25 or so might be a good spot if you shrink it... Depending on how much you shrink it of course.