I think you may struggle to find anything as most workers in Borovets are 'returning workers' and as such there are only a few jobs for 'newbies'. In addition, there are only a few bars / hotels that have DJ's so jobs are very limited.
We can ask around for you if you would like, however you also need to let us know about your salary expectations as I'm not sure if you know what local rates of pay etc are.