BiFi released an update of Palette Editor, a ROM image allowing you to change the default palette on MSX2 and up before booting a cartridge. The fact that it hasn't seen an update for nearly five years until today is not due to neglection, but rather thanks to its creator's perfectionism, improving it once more and perhaps again five years from now.
One of the bigger additions, though not related to fancy colours, is support for forcing MSX1 and non-Japanese text on MSXturboR. For detailed information, screenshots, and a download location, look no further than behind the link below.
Relevant link: Palette Editor