I included turbo training for the 98 etape. First of all did it all with two yellow pages under the front wheel holder thingy. I was a bit ad hoc, and did intervals when had less time just to get a session in. When I had more time but it was raining, had the front wheel raised to simulate gradient, put the resistance up as much as I could bear and then tried to keep going for an hour and a half or more.
Not massively sophisticated but I got fit enough to get round without having to worry about elimination. Tourmalet was mentally torturous. Hautacam wasn't as mentally bad, but somewhat slower!