Have you tried downloading a utility called LOPE? It lets you edit/add/remove pylons and weapons through a simple interface. Aside from that, when you want to get into fine-tuning payloads by manually editing the meinit, use Notepad to edit.
"To be afraid of living is to be afraid of dying. How can you get past this, and cherish the fear of flying?"-Juliana Hatfield
WORDPAD & NOTEPAD are two "WORD EDITING' programs on the order of a simplistic WORD PERFECT IN OTHER WORDS BOTH OF THEM ARE "TEXT EDITORS"
NOTEPAD is the simplest although i prefer WORDPAD. Both are programs that are included with your OPERATING SYSTEM. Go to START PROGRAMS ACCESSORIES you should find one or both programs there.
Keep in mind that certain weapons won't work on player aircraft, such as cruise missles of sorts. However, anything laser-guided should work on the A-10, and Su-25 (normal and 'T' version).