How to replace motorcycle handlebars that have a throttle tube?

It's a1974 honda cb125s. The stock bars have a throttle slide (11st one I've seen ). How do I replace the bars with clip ons?

Are the throttle slide clip ons? Or do I convert it to what I'm used to using?

Wow! I must be getting old.
I actually knew what you were talking about "throttle slide"
http://www.cmsnl.com/honda-cb125s-1979-usa_model7204/partslist/?model_q=cb125
You can either get creative and cut the clip on to allow for the throttle contraption.
OR purchase a regular throttle pipe & right handlebar switch from a different model and purchase a custom made throttle cable.
http://www.motionpro.com/motorcycle/tools/category/cables/

Another problem you will have when installing clip ons is, the headlight is held in place by fork covers that cover the fork tubes.
You will have to modify the headlight mounts.