Actually, you don't need status to select E+ seats on ps. United.com will allow anyone to select E+ seats only for p.s. flights. The seats will show as green (vs E- blue). However, you can still select them. There will be a warning pop-up window warning you that E+ is reserved for elite blah blah. Just click OK and you will be booked.

You can do a dummy book without signing in to see for yourself.