I've tried changing build/target/product/core_minimal.xml with
PRODUCT_RUNTIMES := runtime_libdvm_default
PRODUCT_RUNTIMES += runtime_libart
PRODUCT_RUNTIMES := runtime_libart
but it caused a bootloop
EDIT: I tried the build again this time using
PRODUCT_RUNTIMES := runtime_libart_default
, and this time, it refused to start up. I pulled the battery, put it back it, and all of a sudden, it started working, buggy yes, but at least it booted up. When I went into dev settings expecting to see no option to change runtime, I saw "libdvm.so", "libart.so", AND "libartd.so". Well that didn't work out as planned....
EDIT2: *sigh* I swear my phone is playing with me. Or maybe 2nd time is the charm. But it worked flawlessly. Trying a 3rd time with gapps this time.