It's not so difficult. You can try one or some of these points: 1. submit your site at siteexplorer.search.yahoo.com/submit 2. make advertise on yahoo 3. Signup Yahoo!Groups and put your Links there 4. Submit your site at Yahoo!Directory (see: ecom.yahoo.com/dir/submit/intro/)
Replay a good answer in Yahoo "answers.yahoo.com" , if your site is indian based then answer in "in.answers.yahoo.com" to get backlinks and easy way to index in yahoo
if you want more back links with yahoo so do work Do follow and also No Follow sites for the reason that yahoo consider both Do follow and No Follow...
the best way to get backlink from yahoo is by joining yahoo group and leave your site urL there. But remember, dont be spammy
Submit your site in Yahoo webmaster tool Submit site in Yahoo local business listing participate in yahoo answers
Submitting your site to Yahoo webmaster definitely does the trick. If your using wordpress, just add the code to the all in one seo plugin and yahoo will crawl your site quick.