Changing Z-Height While Maintaining Y Velocity

I would like to perform multiple moves in the Z axis while maintaining a constant velocity along the Y axis. For example, I would like to be able to execute something similar to:
G1 X1 Y1 Z1
G1 Y3 Z1
G1 Y5 Z2

...without decelerating and then accelerating again in the Y direction.

Is this possible? I am using a Shopbot PRSalpha Buddy with a Mesa 7i76 board and LinuxCNC. I have tried using G64, but still get more acceleration along Y than I would like.

Thanks!

Is the application plasma torch height adjustment?

Yes, although it's a nonstandard torch for which the typical voltage-based adjustments will not work. We plan to probe the surface to measure height changes.

In that case, you could investigate "probekins"

wiki.linuxcnc.org/cgi-bin/wiki.pl?ProbeKins

Your problem sounds identical.

That module does sound interesting. Do you know where I can find the original source code? The Gitweb link in the wiki is dead. I found an old compiled version on the forum, but I would prefer the source if possible.

Is there no simple G code means to avoid acceleration along one axis between commands affecting a different axis? The module seems like overkill for handling this, but maybe there is no simple solution.

Thanks!

The advantage of that module is that it doesn't require special G-code, any 2D plasma CAM software will work.

As for the second question, I don't know. I have never needed to worry about the trajectory planner with my slow old machines