15 years ago I opened up an HP inkjet cartridge and refilled the black ink with blue ink from the local stationer's store. You had to make sure not to use india ink because it has particles that will clog the jets.
So one possible way to make white decals is as follows. Drain a black cartridge, and maybe flush it with distilled water. Then refill with white ink. Print your white decals (e.g. raleigh model names) with an all-black setting on your printer. They should come out white.
Has anybody tried this ?? i haven't been very successful at finding a source of white ink on the web, and i've been too lazy to visit stationery store just for this purpose.