Simulating Climbing: Front wheel 26" and rear wheel 24"

The extra effort needed to climb hills is because you're climbing a hill, not because the bike isn't level.  So creating an "upward angle" with different wheel sizes or a big block under the front wheel on a trainer isn't going to do anything.

It takes a variable resistance trainer to realistically simulate hill climbing.  Either you crank up the resistance by hand or you use something like a CompuTrainer which is a computer-controlled variable resistance trainer. 

If your trainer doesn't have variable resistance, or you want to simulate hills outdoors on flat terrain, then the usual advice is to increase resistance by riding a big gear such that you're putting out max effort with a cadence of 60 rpm or so. 

BTW, I do a lot of hill climbing because the Seattle area is very hilly. Most every ride involves some degree of hill climbing.  And since I live on a hill, my ride home involves a 500' 5-10% grade.  We have annual local rides with names like "7 Hills of Kirkland" and the "Chilly Hilly".  Yep, we've got hills. 

If you want to simulate that kind of hill climbing, you'd alternate five to ten minutes of high gear / low cadence (the climb) with low gear / high cadence (the descent).  Then repeat.  Over and over.

Echoing the others: it's all about the power-to-weight ratio. The more watts you can generate and the less weight you're carrying, the faster you'll go uphill. Simple as that. It's possible to become quite a good hill climber without ever riding on a hill in training. It can all be done on the flat, or on a trainer. It's the descents that require more specific training, because of the technical skills required.

Also, I wouldn't worry about the low cadence work, unless you're expecting to run out of gears on a climb, either because the climb is so steep or because you're carrying a lot of weight. The most efficient way to climb is to simply shift down to a gear that allows you to climb seated at the cadence that you're normally comfortable with. Standing up to climb can be a good way of generating power, but it's quite inefficient, so it's only to be used as an extreme measure. I have no reservations about using my granny gear to spin up a hill in a race; especially as that generally has me passing lots of people who are straining up the hill in a larger gear, often standing.