try this free program. Download inSSIDer and Discover the Wi-Fi Networks Around You | MetaGeek
it will show you what channels are being used in your neighbourhood, and so you will know which channels to avoid.
ah sorry, reading your post, you say you can't use a scanner as you don't run windows - is that correct?
oh well, i'll leave this post as it is as it may help others.
maybe you can persuade a friend to come over with a laptop to scan for you?
or if you have an android phone, wifi analyser
does a similar job.