Here's the reply if you voted the same way that I did in the referendum
Although I've never veneered a cylinder I have done plenty of veneering on curved surfaces, i.e. parts of cylinder, and they work just fine in a vac bag.
However, if you wanted to complete a cylinder in one shot then the key problem is pressure. I'd be sceptical about segmented cauls, or wrapping bungy cord around the job, or any other such "wizard wheezes". There's every likelihood they'll either take way too long to prepare or that they'll do a poor quality job. Instinctively I'd say the better route is to simply remove the need for sustained pressure, so like Mike suggested use hide glue, or alternatively use an "iron-on" veneer which you can easily make yourself with PVA, or even simpler with commercial sheets of iron-on adhesive. Handling the join is slightly trickier with the iron-on route, but iron-on and hide glue both share the characteristic that the bond loosens with heat so you can use the same, well proven method of overlapping and then trimming back with a scalpel.
Regarding veneering a conical shape I did once do something vaguely similar for a box lid. Mike's right again, the problem there isn't the actual gluing (the same principles apply as for cylinders) the hard bit is orientating the grain. On a cylinder I'd be tempted to use an almost grainless timber like Swiss Pear so the join isn't too obvious, but on a cone I'd be tempted to follow the same steps as in veneering a sunburst and actually accentuate the grain. If I get the time later today I'll dig out a photo of the conical box lid that I did which illustrates the effect.
And here's the reply if you didn't
Just use contact adhesive and a staple gun. It's a breeze and I guarantee you'll be delighted with the result.