How do I configure the Linux kernel within Buildroot?

I'm trying to build a rootfs for an x86 target, which is all simple enough. However I can't figure out how I configure the kernel that buildroot produces. The first run through came up with menuconfig, but it's cached the .config since then and I can't see where to change it. ~650MB of kernel modules don't do good things to an embedded target :P Is there an easy way to configure the kernel within buildroot? Something like the `uclibc-menuconfig` target would be perfect.