Other than painting, how can I cover a cement wall in my basement?

You can use fabric:

https://www.hunker.com/13413737/how-to-hang-fabric-to-hide-basement-walls

You could frame it out and put up panels of sheetrock with insulation between the wall and the sheet rock. s will help with the cold, increase the value of your home and property, and can be accomplished over time as you can afford the materials.

Temporarily? Hang ceiling to floor heavy, light colored drapes or curtains.

I know that you don't want paint, but masonry sealer, such as ThoroSeal or Sunny Dry is the least expensive best looking way to go. Up from that is epoxy basement paints but I have had good luck with portland cement based paints such as these.

https://www.hunker.com/13413737/how-to-hang-fabric-to-hide-basement-walls

Cover it with wall board, or use the textured spray paints they have out now...some are even using contact paper in pretty designs!

You could use something like FlexSeal on all the edges in the room, floor, ceiling, door frames, window frames, wall intersections. Then build a proper (legal) frame, with electrical and other essential connections, placed very near the framework, when possible. Use rolls of insulation, thick or thin, depending on whether this is an outer or inner wall. Then hang paneling of whatever style, color and quality you wish. You can get wallpapered paneling, painted and textured paneling, real or composite wood paneling, and even restored wood and corrugated steel paneling. You could rivet one of these types of paneling to your original wall, but when you get ready to upgrade, you would have the expense of removing the paneling. Best wishes, whatever your choice. 😇

Cover in Old Scaffolding planks?

Is the area just cold and dark or is there a moisture probelm also?