I have played around with this a little. I wanted to get bigger, more colourful flowers than what I was getting on my Soehrensias. What I did was pollinate the Soehrensias (formosa types) with a Trichocereus that was flowering at the time. A Tricho. similar to T.shcickendanzii, but flowered earlier when the Soehrensias have their first flowers. I got some nice plants with various shades of yellows and oranges. Bigger flowers, some with scent, some without and some that even though they were coloured, only opened in the evening like the Trichocereus, most opened with the sun like the Soehrensias. Using a Soehrensia with a very dark red flower, I have managed to get a couple of plants with large pink flowers, very special in my opinion.
The trick is to get plants that are flowering together and go for it! Or, you will have to collect and store pollen. I was playing around with the bigger plants because I have the luxury of plenty of space and I like the big plants. However with Echinopsis and Lobivias you will be able to keep them in pots.
I had a friend grow some of my hybrid seed up on the north coast of New South Wales where the climate was almost tropical. She had plants flowering in three years from seed!! As you could imagine, they grew very lush and didn't have a very nice shape about them. But they flowered. The long-term upkeep of these wasn't easy, they tended to rot and get black marks on them. It took five years for the same plants to flower for me with a cold winters rest, but the plants are compact, healthy and looking good.
The smaller growing Lobivias and Echinopsis may be able to be 'forced' in the same way, I don't know. What I do know, it's fun! Good luck. Joylene.

Thanks for that Joylene,
I was wondering - seeing we are at a similar latitude - if you could talk me through your seedraising set up? I am going to start building the seed raising stage at the beginning of November (when my broken finger is properly healed!!). Any ideas would be good...I have 2 large white fl. Tricho' plants already, plus white fl. Echinopsis plants, but only 2 young Lobivias (at the moment *grin*)...I also have Gymno X seeds and Echinocereus X seeds from last season...they will be my first seed raising attempt this year, once I get it right, I'll get serious with the plants I really want results from!
Thanks again,
Wazzimodo

You should join the Succulents_Grown_in_Oz group. It covers the whole of Australasia with quite a number of the movers and shakers of the C&S fraternity involved. Do a google search to locate it.