Although the Outer Hebrides had been Christianised for a long time, many early (but still "modern") visitors did record some surviving pagan characteristics within their customs. It's worth having a look through Martin Martin's
A Description Of The Western Isles Of Scotland, from around 1695, for such an account, or check
Description of Lewis by Captain Dymes, who visited Lewis in 1630, for an example of one of the ways in which Christian saints were venerated as (and sometimes directly mapped onto) earlier gods. No Wicker Man or anything like that, but it is a very interesting subject.