what drive do you use? I am aware of minimum write speeds between 8x and 16x (depending on the drive) for modern DVD writers. 24x is very uncommon.
I mean trial versions of different burning software do it somehow.
Not really. The minimum CD-R write speed depends on the media and the drive you are using. No piece of software is able to override this limitation although some softwares indeed allow to set any speed you want - but this setting might just be ignored by your drive.
I would like to get it down to 1-4x.
Unless you can get your hands on an ancient 16 CD writer - no chance.
You may run either Nero CD/DVD Speed and check the “Disc Info” tab or use Imgburn and have a look into the right pane after having inserted a blank disc. This will show you the speeds your drive supports with that particular blank media.
Since you have readability problems with a disc written at 24x, then either your media are mediocre at best or your drive isn’t a good CD writer. Or both is applicable.