Line 28 was not working properly and has been fixed. You will now slide continuously along the ground at the speeds set in lines 26/27 if you have it enabled. This is best used for auto-pathing.
I have checked and confirmed that ship speed works with slide speed; however, you will want to press F9 (or whatever key you have set in line 34) beforehand to disable all animations. I have added this information to the online Speeder guide.
The line 28 fix requires updating Speeder to version 43.