When I had to liquidate my 401k/ESOP back in 2008 in order to use NUA on the company stock I wished to cash out, I had some after-tax contributions in the 401k. Although I could have conceivably done a direct rollover of those after-tax contributions into a Roth IRA, I decided instead to take them as cash in order to pay some of the taxes on the cashed-out company stock. I simply asked the plan administrator to send that money, along with the proceeds of the company stock, into my local bank's checking account. The after-tax contributions were, of course, not subject to any further income taxes and the 1099-R form reflected that.
The rest of the 401k, other than the company stock cash-out and the after-tax contributions, I chose to do a direct rollover into an IRA. There were no income taxes due on that, either. I had no taxes withheld from anything although I did have to make some estimated tax payments on the NUA.
Retired in late 2008 at age 45. Cashed in company stock, bought a lot of shares in a big bond fund and am living nicely off its dividends. IRA, SS, and a pension await me at age 60 and later. No kids, no debts.
"I want my money working for me instead of me working for my money!"