As a biologist and a language freak, here's my take:

While 'heterozygous for albinism' is a mouthful, it's the most accurate; 'heterozygous albino' is also correct. 'Albino heterozygous', though, is just wrong -- 'heterozygous' is an adjective, not a noun. You'd have to say 'albino heterozygote' and, while that's correct, it doesn't actually provide any link between the albinism and the heterozygosity -- it could be an albino (ie, full albino) which is heterozygous for some other trait.

Cheers.