And also to consider.....

...make a mistake and start over - hours wasted.

...program bug makes it necessary to re-assemble or re-compile. then start over - hours wasted.

...soon new ideas lead to new code features. time to enter yet again - more hours wasted.

...By this time the effort required could have permitted you to take the time to build one of the low cost programmers you can find plans for here on the WEB.

But better than all that get your self away from old EPROMs and dig into using a ISP based processor with onboard FLASH. The ISP downloaders are either low cost or simple to build.
Mike Karas