Overriding scala library with scalac

Hi,
I just wanted to override scala library used for compilation with scalac. After a bit of fight I came up with following solution:
./scalac -nobootcp -bootclasspath ~/scalagwt/scalagwt-scala/build/quick/gwt/library test.scala
It works only if I alter scalac bash script a bit:
    -nobootcp)      CPSELECT="-classpath "      # USEJAVACP=true      shift       ;;
look at commented out line. I couldn't decipher from looking at bash script what's the logic behind that line...
--
Grzegorz Kossakowski