I cross-compiled node using the entware toolchain using the following commands.

export CFLAGS='-mips32r2 -mtune=mips32r2'
export CXXFLAGS='-mips32r2 -mtune=mips32r2'
export LDFLAGS='-Wl,--dynamic-linker=/opt/lib/ld-uClibc.so.0 -Wl,-rpath,/opt/lib'
export AR=mipsel-linux-ar
export CC=mipsel-linux-gcc
export CXX=mipsel-linux-g++
export LINK=mipsel-linux-g++

./configure \
--prefix=/opt  \
--dest-os=linux \
--dest-cpu=mipsel \
--with-mips-float-abi=soft  \
--without-snapshot

make