OK, here's the setup I've got for my portaband. It's not a Harbor Freight, but a Milwaukee, but from all I've read about the HF saws, they should do what you're looking for nicely.

If you look, you'll see the U-bolt clamping the saw handle to the wooden board. An angle iron is bolted to bottom of wooden board, the "C"-clamped to a table saw top. The saw handle is sitting in a cutout on table top, and while not "perfect", it's plenty steady for routine cutting. Also easy to remove and use as PortaBand saw when needed.
The table is a 6"X6"X1/4" aluminum plate with a slit cut for saw blade, and screw holes to bolt down.
Nothing fancy, but it works.
Ken H.

If you look, you'll see the U-bolt clamping the saw handle to the wooden board. An angle iron is bolted to bottom of wooden board, the "C"-clamped to a table saw top. The saw handle is sitting in a cutout on table top, and while not "perfect", it's plenty steady for routine cutting. Also easy to remove and use as PortaBand saw when needed.
The table is a 6"X6"X1/4" aluminum plate with a slit cut for saw blade, and screw holes to bolt down.
Nothing fancy, but it works.
Ken H.