not quite sure what you are after, do you mean that you want to be able to press the key and the character moves smoothly left or right for a certain distance?
I had this in mind as a kind of solution (needs a little playing around with tho
)
set display mode desktop width(), desktop height(), 32
autocam off
position camera 0,0,0,-100
point camera 0,0,0,0
make object sphere 1,1
sync on: sync rate 60
movement=30
speed=1
do
if leftkey()=1 then xtarg#=object position x(1)-movement
if rightkey()=1 then xtarg#=object position x(1)+movement
if object position x(1) > xtarg# then xpos#=object position x(1)-speed
if object position x(1) < xtarg# then xpos#=object position x(1)+speed
position object 1, xpos#, object position y(1), object position z(1)
sync
loop
This is not the Sig you are looking for....