You could try installing over Apple's curl binaries (this is what I do). I gave instructions in a post below.
checking for CURL in default path... found in /usr
occurs when the ./configure has "--with-curl" or "--with-curl=shared" (latter is unsported on Mac OS X). instead of "--with-curl=/sw". Thus, that line should not be output if youy have "--with-curl=/sw".
is only for targeting the make install. It shouldn't affect the configure
The version of curl I install against is 7.10.3 from fink. I am using "curl-ssl", "curl-ssl-dev", and "curl-ssl-shlibs" packages. You definitely need either the "curl-dev" or "curl-ssl-dev", and the library is in "curl-shlibs" or "curl-ssl-shlibs" so you'll need that too. I don't think the "curl" or "curl-ssl" is needed, but it doesn't hurt to have it also.
Unfortunately, I also smash Apple's installation of curl on my machines with my own, so I can't be 100% sure that PHP isn't accidentally linking against that.
I hope this helps,
tychay at php dot net