just use the normal handicap system ( with a slight butcher )
if playing a par 72 course
player has average 73, then the player receives +1 stroke
(on the hole with stroke index 1 - see note on stablefords)
player has 71 average, then the player receives -1 stroke
(on the hole with stroke index 18 - see note on stablefords)
if playing a stroke play tournament the above is simple to calculate, just need to adjust handicaps based on which course is played for the par.
stablefords can also be played using the stroke indexes of the hole ( will need research on the club websites )
a player with -1 handicap will lose 1 stroke on index 18 (the easiest hole), so if it is par 4, the player is now playing the hole as a par 3
while a player with +1 handicap has 1 stroke added to stroke index 1 (the hardest hole), if par 4, then the player is playing the hole as a par 5.
if par 70, player has average 63 ( so -7), the player loses a single stroke on holes with stroke index 12 through 18.
player has average 77 ( so +7), the player gains a single stroke on holes with stroke index 1 through 7.
this would be quite simple to track in a spreadsheet
see below for how i track my society stableford score
http://www.solentgolfsociety.co.uk/resultssheet.html
note also, it is up to you whether or not to use the wgt "average or keep track of the real average