Yes I understand what you are trying to do.
I don't think there is a similar function in LR, however I don't know if you've noticed on the Tone Curve section, just to the left of the of the curve box a small circle shaped icon. Move the cursor onto it and you'll see ^ marks appear above and below. It will also cause a dialogue box to appear "Adjust Tone Curve by dragging in photo" . Click on this and you'll see it become lighter, this means its active. You can now drag this onto the image, select an area you want to adjust in the photo, then click and drag up or down and it will adjust the appropriate area in the tone curve.So you could use this to set you highlight white point.
I don't know how long this function has been in Lightroom but I only found out about it a few weeks ago in the Adobe LR user to user forum.
Hope this helps