You can, as a teacher, support a learner with HIV/AIDS through showing compassion for them in their situation, while at the same time challenging them to rise above their situation through their education. Their having HIV/AIDS has its own set of challenges, therefore, their academic studies can be a part of their lives where they can grow as individuals and better themselves - they can be a fine example to others who face the same, similar, or even different challenges. Your job as their teacher is to support them in realizing their potential, despite their physical health.
Consider that HIV/AIDS learners may have faced discrimination at various times since their diagnosis. They may or may not have the support of family, relatives, co-workers, friends, and acquaintances. Therefore, you, as a teacher, may be their sole source of compassionate support. This entails going beyond offering academic instruction, and supporting them as human beings who just happen to desire to learn a skill, trade, discipline, and such. Your role as an educator is to offer them support beyond textbook learning and support them in many areas that, combined, give them the best chance to achieve success in life - with the added benefit of having an academic foundation to support their efforts.
All told, you would support an HIV/AIDS learner as you would support anyone who is battling a physical disease, such as cancer, heart disease, or whatever. They don't want special treatment from you - they want to be treated as equals with all other learners and have the same opportunities to achieve as anyone else does.