That can be done but you'll have to monitor and be flipping the switch on each of the wash/spray rinse/deep rinse/spin cycles which is taking the "automatics" portion of the washer back into a semi automatic washer. Just one tiny step away from a wringer washer, really. That's not for me in this stage of my life but in my younger years I'd probably do it...for a while.
You can purchase a new or used timer from a 310/410/710/810 on Ebay and remove the timer motor, which is probably going to be your only choice. The only other option is to look for a very cheap or free washer, remove the timer or motor and part the rest of the machine out. You could actually get your money back and more using this method. 10-15 years ago when these were everywhere and free on craigslist, this was very possible to scrounge what was needed. Now, they're drying up and word is out that these washers are better than any top loader made today, have more options, more flexibility, and no dumbed down temps so they go for stupid prices in most areas. I knew this would eventually happen.