-> install build dependencies:
$ tce-load -wi compiletc gtk2-dev intltool

-> download glib2-dev.tcz (http://tinycorelinux.net/9.x/x86_64/tcz/glib2-dev.tcz), unpack it, copy the lib*.la files into /usr/local/lib/

-> make two edits to the source code:
1) in aclocal.m4, change this line:
  gentoo_ltmain_version=`grep '^[[:space:]]*VERSION=' $ltmain | sed -e 's|^[[:space:]]*VERSION=||'`
to this:
  gentoo_ltmain_version=`[grep '^[[:space:]]*VERSION=' $ltmain | sed -e 's|^[[:space:]]*VERSION=||']`

2) in configure, change this line:
  gentoo_ltmain_version=`grep '^[:space:]*VERSION=' $ltmain | sed -e 's|^[:space:]*VERSION=||'`
to this:
  gentoo_ltmain_version=`grep '^[[:space:]]*VERSION=' $ltmain | sed -e 's|^[[:space:]]*VERSION=||'`

-> per TC wiki, for maximum compatibility:
$ export CFLAGS="-mtune=generic -Os -pipe"
$ export CXXFLAGS="-mtune=generic -Os -pipe"
$ export LDFLAGS="-Wl,-O1"

-> finally:
$ ./configure --prefix=/usr/local
$ make
$ mkdir /opt/dest; sudo make DESTDIR=/opt/dest install

-> manually create /usr/local/share/applications/gcolor2.desktop and /usr/local/share/pixmaps/gcolor2.png