Posting a follow-up for those who might search after me...
I had very good success applying OSMO Polyx-oil by hand. Emboldened by Tim's experience, I and a friend spent about 15 man-hours to apply the first coat, and it took me by myself about 9.5 hours to put on a second coat. This was for approximately 970 sq. ft (sorry, we still use imperial measures here in the US ... sad, that) of white oak. The floors were not new, although I don't know their exact age. (Although the fellow who sanded them cautioned me that this was probably the last time they should be sanded.)
The floors had been sanded to 100 grit, and then sat for about a week (we're not living there yet, so I didn't have to put anything over them, just didn't walk on them) before I could start finishing.
The special brush didn't arrive, so I purchased a foam pad applicator,
9 inches wide .5 inches thick and with some short soft bristles, and a stiff plastic-bristled brush. We used the pad to apply the oil evenly, and then the brush to kind of scrub it in. This was hard on the knees, so when I had to continue the first coat by myself, I used just the pad at the end of a pole. This seemed to work just as well, although I was glad that I had had the experience of being close to the work initially, to have a feel for how the oil worked its way into the wood.After a few days drying (the luxury of doing your floor _before_ moving in!), I applied the second coat in one afternoon and evening, using just the pad. I had a kind of rhythm of apply, then scrubscrubscrub, then smooth, doing areas of about 6 to 8 sq. ft. at a time.
While the floor seemed rough and slightly scratchy after the first coat, I did not sand between coats. After the second coat dried, I was pleased that the floor has a nice smooth low-gloss look and feel.
The only problems I had, really, were that because I worked so late into the night several times, I had limited light available (have to turn off the switch in the room while you can still reach it, right?!). When I inspected my work the day after applying the second coat, I found some spots, mostly in the last room I worked in, where I had not applied the second coat heavily enough, so there were voids/dry spots. These were easily retouched. There were a very few spots that I had not smoothed, and I trust that I will be able to sand/steel wool these in a few days, or that normal wear will ultimately knock off these higher spots.
Overall, I applied the oil pretty conservatively, using about 6 liters total; the website instructions (and my inspection and subsequent retouching) imply I might have used a little more.
My thanks to those who have contributed to these forums -- I was nervous about doing this, but found reassurance here. I hope others will find the same.
Jacque