The only issue I experienced on my PAL C64 is the tuning appears to be slightly
too low. I
always have to set the tuning to -40 and play everything one semitown lower!

I know two ways to get paddles on your C64:

1) Using a 470K log pot:

connect the pot terminals#1 and #3 to Joy port SUB-D #7 and #8. Terminal#2 (the
wiper)
to SUB-D #9.

-----------------------> pin #8 (GND)
/
\ <--------------------> pin #9 (potx)
/
\
-----------------------> pin #7 (+5V)


2) Using a 100K lin pot and 4.7nF capacitor:

check this schematics
http://www.firestarter-music.de/prophetcart/pots2.jpg

YouŽll only need the pot connected to pin#5 (#9 = pot-y, not used with
cynthcart).
Terminal#1 and #2 are interconnected and terminal#3 goes to SUB-D #7. There's a
capacitor between SUB-D #5 and #8.

This solution is little more explained there:
http://prophet64-forum.com/viewtopic.php?id=173&p=2

Good luck!

r.