Hi David,
you can use lascopy64 with arguments -match_xyz 0.5
If you want to have different from xy values for z it is probably easiest to scale z before to the same dimension like xy, do the copy and then scale back:
las2las64 .... -scale_z 50
lascopy64 ... -match_xyz 0.5
las2las64 ... -scale_z 0.02
Cheers,
Jochen @rapidlasso