Flight Plan Altitude in FS 2

Hi there. I have a question. When I generate a flight plan on the Navigation screen it assigns altitudes for all the waypoints. Is there any way to change those altitudes either from the FMC or the Navigation screen itself? I couldn't find a way to do this. I usually fly the Learjet and it is fabulous, even VNAV works OK once you get the hang of it so being able to change the altitudes before starting the flight would be perfect. (I understand that this feature is present in FS 4, but unfortunately I'm stuck with FS 2 for the moment).

Thank you.

Quote from Jet-Pack (IPACS)

You can try and set the cruise altitude in the CDU or MCDU of an airliner. But there was no navigation menu cruise altitude adjustment back in Aerofly FS 2.

I know, that's why I was looking for a workaround to that. Thanks Jet-Pack !