There are tons of threads on slider icons. What manila version are you using? You can look in the Manila subsection of software and find lilrico's icons for sprint stock manila based ones, look in the diamond theme section at xda (I think someone put a cab together of the 2.5 color icons recently), etc. etc.
Here's one link if you're using manila 2.x:
http://forum.xda-developers.com/showthread.php?t=553771