How to use different accounts (of different countries) for iTunes and iBookstore on iPhone or iPad? Simply stated, it is I bought quite a bit of Music and Movies from my native country (be it Hong Kong, France, Italy, etc).  However, the iBookstore for that country has very few books on the iBookstore.

Therefore, I need to listen to music and watch movies for iTunes store for one country (Hong Kong), and be able to read books on iBooks for the content of USA iTunes store, on the same iPhone or same iPad.

Is it possible?

(some details: it looks like if I keep on switching countries using one iTunes account and buy content from USA store and Hong Kong store, then all content can be available under one iTunes account and therefore on one iPhone.  However, since I don't have a credit card with a Hong Kong billing address, I can only buy HK gift cards and buy HK content that way, and I can't switch to USA store and buy things if there is remaining HK$520 in the account.  I have to use it all up first.  So I am sort of forced to use 2 iTunes accounts, one for the HK store, and one for the USA store.)
I have a Canadian iTunes account and a USA iTunes account that I switch back an forth with on my MacOS X system - mostly because some iOS software is only available in one country or the other. Purchases from each account seem to be syncing just fine to my iPhone, so I assume it will work for books too.