Hi NeOCzx
There are some imporant differences between GLCD v3 and U8glib. While porting is for sure possible, there are some restrictions on U8glib, which are not present for GLCD lib. GLCD and U8glib have two completly different programming concepts. It might require much more than just replacing the drawing primitives.
I suggest reading the article here, before porting:
http://code.google.com/p/u8glib/wiki/tpictureloop
Also, Bill's library is highly optimized and much faster than U8glib. On the other hand, U8glib should be more flexible regarding the graphics hardware.
One result of the different concepts is that there is no clear screen available in U8glib. The screen is cleared as soon as you enter the "picture loop".
Oliver