It's basically a rollover IRA. So there's no IRA limit on contributions per year. Once the account is opened, it would be in a regular cash account or money market account and then you can just buy or sell shares whenever you want and it can all be done online. Normally you would do a trustee to trustee transfer but because the CARES act treats putting the money back in as a trustee to trustee transfer, there's no downside to doing it that way aside from missing the gains/losses while the money is out of the market.
Or I suppose just a regular cash account in a brokerage account. But dividends and capital gains would be taxed every year unlike an IRA or Roth. I don't think that puts you ahead over the long term even though you avoid the 10% penalty. Best to just spend what you need and then put the rest back within 3 years.