You can activate the launcher in steam: Right click on the game in the list and select "Show game launcher". This will start the game launcher before starting the game, just once.
In short: Just execute "xset -r" on the command line/in a terminal window when playing 7d2d and afterwards execute "xset r" to reenable keyboard auto-repeat (if you want it back). You can execute the command any time, even when 7d2d is already running, it works globally and immediately