I've just picked a place in the casting where the thickness was OK, and drilled through, then scraped or machined a distributor groove in the underside of the moving part. The first one I did was the old Logan's carriage. Might have a pic or two around. The through holes I make smaller than the oiler recesses..... no smaller than 0.078 though, Vactra doesn't seem to like going through smaller holes.
The V-side I just drilled down to the top of the V, where there is some clearance. Scraped a little area to be a distributor, and counted on gravity to move oil down to the surfaces. Worked OK. On the flat side, the only place for the oiler was not in a good location, so I added a piece of copper tube to drip the oil on the way in the gap where the screw was, and scraped a lead-in on each side to funnel oil under with movement.
I put flip-top oilers on, because the ball oilers get covered in chips, the oilers were right near the crosslide of the carriage. I'll say that neither type is ideal, but the flip tops hold more oil. A one shot pump would be way more suitable.
To me, the compound is a "maybe", the crosslide is a "yes". The compound I tend to move way less, which may be a good reason to give it oilers, so that it is right there begging for oil and doesn't get neglected.