As Bolivia is [not yet a member of Mercosul][1], there are no differences from any other nation for immigration, as far as I know.

The usual way is to go to Brazil with a tourist visa (usually lasts for 3 months, can be renewed for more 3) and look for a job there. With some luck, if you find a job, the hiring company can start the process with the Ministry of Labor. After it, if the Ministry granted the authorization, you have to go back to your country, get in touch with the Brazilian consulate (filling some paperwork in the meanwhile - a letter from the company that is willing to hire and a form with personal data). The consulate will then evaluate your request and eventually grant the temporary working visa. 

The complete process is described [here][2] (in Portuguese).


  [1]: http://en.wikipedia.org/wiki/Member_states_of_Mercosur
  [2]: http://www.portalconsular.mre.gov.br/estrangeiros/tipos-de-vistos/vistos-temporarios