Try this: https://addons.mozilla.org/en-US/firefox/addon/ctrl-number-to-switch-tabs/
If it doesnt work, your best option is to either find another extension that does. or bite the bullet and configure a key remapper like keyd and make a "layer" to toggle the bind alt+(num) to ctrl+(num).
Try this: https://addons.mozilla.org/en-US/firefox/addon/ctrl-number-to-switch-tabs/
If it doesnt work, your best option is to either find another extension that does. or bite the bullet and configure a key remapper like keyd and make a "layer" to toggle the bind alt+(num) to ctrl+(num).