Hi.
I hope this maxscript will do what You are asking for.
mods =for each in $.modifiers where classof each == RC_Spline collect each
for each in mods do
(
each.mkuserid[1]=0
each.mkuserdata0[1]=0.0
each.mkuserdata1[1]=0.0
each.mkuserdata2[1]=0.0
each.mkuserdata3[1]=0.0
each.mkuserdata4[1]=0.0
each.mkuserdata5[1]=0.0
each.mkuserdata6[1]=0.0
each.mkuserdata7[1]=0.0
each.mkuserdata8[1]=0.0
each.mkuserlabel0 = "User Data 0"
each.mkuserlabel1 = "User Data 1"
each.mkuserlabel2 = "User Data 2"
each.mkuserlabel3 = "User Data 3"
each.mkuserlabel4 = "User Data 4"
each.mkuserlabel5 = "User Data 4"
each.mkuserlabel6 = "User Data 5"
each.mkuserlabel7 = "User Data 6"
each.mkuserlabel8 = "User Data 8"
)