You need to find the block drain plug and screw one in there. I have no idea where its at on the 3s though so someone else will have to chime in on that.
If you can't find that, they make inline coolant heater/pump setups that T-Off into your coolant lines to heat up and circulate coolant. You hook it up when needed, and remove it when not needed.
Is there a block heater for the 3sgte??
You'll need to measure or know the diameter of an engine freeze plug, knock one out, and install the block heater into there. They're a universal fit product, so once you know the diameter you need they're easy to find for purchase however installation is somewhat difficult if you're not comfortable punching out freeze plugs. You can find how-to videos on YouTube easily to gauge your interest.
2000 Celica GTS 'slowest gts evar'1998 Mazda 626 FS-DE/CD4-E