How I can configure my Yahoo! and Hotmail account to use IMAP?
Yahoo! Mail does have IMAP at
imap.mail.yahoo.com, but you have to send a nonstandard command pre-login, namely
ID ("GUID" "1"). There are some modified clients available to do this, you can find some here.
Hotmail does not have IMAP, but does have POP3 available at
Neither Hotmail nor Yahoo! Mail provide IMAP service.
Hotmail does have POP3 at
pop3.live.com (over SSL on standard POP3/SSL port), but it is very limited in comparison to IMAP.