How to use .htaccess and mod_rewrite in 1 host-3 domain environment?

I have one hosting account and three domains.

What's the best way to write rules to .htaccess in following situation:

- one account, three domains (domain.cn, domain.fi, domain.com)
- need to redirect these to three subdirs (CN, FI, EN) SO that full path is visible in browser
* (www.)domain.cn redirects /CN/ and shows as http://www.domain.cn/CN/
* (www.)domain.fi redirects /FI/ and shows as http://www.domain.fi/FI/
* (www.)domain.com redirects /COM/ and shows as http://www.domain.com/EN/

I do have a fully working and smooth rules currently which in fact hides those subdirs from browser's address field. However, I want/need them to be visible.

I guess answer is simple, however I'm missing something and can't get it to function like described above.