alternate configuration step with cmake rather than ./configure

[Jonathan Tomshine]

I'm attempting to make a portfile for an application that uses cmake
for its configuration step, as opposed to the standard ./configure.
I'm running into a confusing error with regards to my alternate
configure{} though.  My configure stage is this:

configure {
    exec cmake ${worksrcpath} \
    -DWITH_CFITSIO=OFF \
    -DWITH_FLI=OFF \
    -DCMAKE_INSTALL_PREFIX=${destroot}${prefix} \
    -DNOVA_INCLUDE_DIR=${prefix}/include \
    -DNOVA_LIBRARIES=${prefix}/lib/libnova.a
}

(adding the ${worksrcpath} behind cmake shouldn't be necessary, but it
delays failure from the configure to the build stage)

For whatever reason, my alternate configuration step appears to be
running in the directory:

/opt/local/var/macports/sources/rsync.macports.org/release/ports/devel/openssl
(?!?)

Based on the macports manual:
http://guide.macports.org/#reference.phases , it appears that it
should be running in ${worksrcpath}, which it certainly isn't.  Since
"cd" seems to have been specifically disabled, I'm at a loss as to how
to fix this problem.  Do I just need to copy all of the resulting
configure files to ${worksrcpath} manually?  Surely I can't be the
first person to use cmake to write a Makefile, so this must have been
addressed before...

Any advice will be appreciated,
-Jon