This combo: you have GitHub Pages on your own domain. On the DNS side you need to point a record to yourusername.github.com but because CNAME cannot live on the same level as your other DNS entries you have to use a subdomain like www and the redirect people from the main domain to the www extension using something like the wwwizer.
This is unless you know that DNSMadeEasy provides something called the ANAME record. ANAMEs are not a new type of DNS record by the way. Behind the scene DNSMadeEasy is going to resolve the target domain and expose a A record in the queries. Problem solved.
$ dig xo.pe ; <<>> DiG 9.8.3-P1 <<>> -t A xo.pe ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6547 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;xo.pe. IN A ;; ANSWER SECTION: xo.pe. 1741 IN A 18.104.22.168 ;; Query time: 40 msec ;; SERVER: 22.214.171.124#53(126.96.36.199) ;; WHEN: Sat Mar 23 21:42:52 2013 ;; MSG SIZE rcvd: 39 $ ping zimbatm.github.com PING zimbatm.github.com (188.8.131.52): 56 data bytes ^C