After coming up with some sort of vague premise, I suppose the next stage in the 'design process' (oh god, theres a phrase I haven't heard in a while. I'm having flashbacks to year six woodwork lessons) would be to do some research. Aside from watching old westerns theres not a lot of obvious starting points. As far as I know theres no obvious precident for what I'm trying to do (I suppose David Peace's books set in Yorkshire kind of have the same vibe but they're more like a Leeds version of film noirs). 
Everyone knows the cliches of country music and the west, its now just a case of finding 'translations' of them which give the impression of 'countrification' (I'm claiming that word as my own) without being too daft.so,
Stetson - Flat cap
Sleazy saloon bars - Sleazy saloon bars (even better if they have swing doors)
Wanted poster - 'Have you seen this man?' ( /cat )
Gun fights - Leeds city centre on a Saturday night
Whorehouses - Holbeck of an evening
Goldrush - Hundreds of students who chose Leeds because 'its where the Kaiser Chiefs came from'
Poker games turned violent - The arcades
Cowboy boots - Cowgirls on a hen night
'I shot a man in Reno, just to watch him die' - 'I went to Wakefield once, and nearly got my head kicked in'
You get the idea...
