Sorry for the late reply! I have tried batch after batch of true-to-style Bohemian Lager, and I would add that you MUST use very, very soft water to brew with. If you can get spring water with low ppm's (50 or so) of hardness you're off to a good start. Harder water will not give you the soft bitterness you need even if you hit 40-45 IBU's. My best Bohemian lagers were around 32-36 IBU's. If you step-mash, obviously use German malts since Czech malts are no longer available. Try Weyermann's Bohemian pilsner malt, and if you want a bit of soft malt character and a beautiful deep gold color add some Weyermann Cara-Hell malt.
I'm a huge proponent of decoction mashing when using German/Czech malts, but if you step/infusion mash, you may need to add a bit of light munich malt for some sweet malty notes this style demands. I'll leave the mashing regimen up to you!
I typically first-wort hop with 1/3 of the hops, add another 1/3 for bittering, and 1/3 for the last 20 min., which is how the Czechs do it. As for aroma, this is where I fall short, but I just bought and read something very, very interesting that's buried in Greg Noonan's New Lager Brewing on page 160. He says to add a hop tea extract from 1/2 oz of hops per 8oz of wort (not water) added post-primary for aroma. This, he claims, adds a milder and spicy aroma instead of a weedy/grassy aroma if dryhopped. This is exactly what I pick up from fresh Czech pilsners. I haven't brewed a lager in 3 years thanks to divorce/move/newly married/no lager chest, so I'm anxious to give it a whirl.
Finally, I love the Budvar #2000 Wyeast. It's malty, clean, easy to use and a good fermenter. When St. Patrick's of Texas introduced it they recommended the temperature be crashed from 50F to 32-37F without a diacetyl rest or gradual ramp-down. This crashing of temperature locks in the malty sweetness of the beer without any detriment of flavor/aroma, and I have done so numerous times with this yeast with great results. Don't think I'd want to try it with other lager yeasts, however!
Hope this helps!!! Sorry I'm windy tonight.