Depends on what type of slide it is. If it's cable actuated then the over ride will be above the slide, in the center and you need a flexible shaft with a square drive bit. Most often you have to remove the top facia for access.
If your slide is electric, then you need to look underneath. One of the racks that the slide rides on will have a "ram" on it,That is the motor side. Now draw an imaginary line across the bottom about 3/4 the way across. You may have to cut an access panel, if you do just cut 3 sides and make it a flap. Look up inside and you should see the motor and gearbox. There should be a rod with a hex head to turn the gearbox.
Hope this helps!!
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.