to make your script fit any screen size, try this tricks :
1- get the screensize :
w=xbmc.getwidth()
h=xbmc.getheight()
2- you know that you made the skin in your own format (i guess it is pal format so 720x540 ; ntsc is 720x480). so the sizes you gave in your script are for pal screen.
just calculate a 'ratio' between your screen size and any other size : (your size is the reference)
xratio=float(w/720.0)
yratio=float(h/640.0)
3- now you'll have to tell all objects, taht x;y positions and w/h size have to be modified with the ratio. don't forget to say the result should be integer
examples :
self.addcontrol(xbmcgui.controlimage(int(xratio*158),int(yratio*25),int(xratio*520),int(yr
atio*500), self.home+'lyricspanel.png'))
self.fadelabel = xbmcgui.controlfadelabel(int(xratio*270),int(yratio*95),int(xratio*255),int(yratio*25), 'font14','0xffffffff')
...
notice that xratio apply to x position and width
yratio apply to y positions and height
maybe sometimes, you'll prefer to make a position 'fixed' so play a bit wether you should use ratio for a value or not !
i hope this can be understandable...(i.e can you understand what i'm trying to explain

)