Yes, you can use Tong Ren on yourself - although for a variety of reasons it is best to have someone else work on you. It doesn't have to be a practitioner per se, just a family member, a child, etc. Anyone is fine. There is also a website, Tong Ren Station .com which broadcasts many of our energy healing classes from around the world. Within this site you there is a chat screen and they will take cases over the internet. There are also a number of conference calls (in the US) that are available for just the cost of the call.
With regards to not practicing qi gong on your own patients because it weakens you - this is incorrect thinking and you should get past this as quickly as possible. If anything, working on others makes you stronger, but I've offered my views on this is previous posts such as this one on emotional transference. Also, learning and practicing Tong Ren instead of more traditional medical qi gong techniques will be beneficial both for yourself and your patients. Tong Ren has many unique aspects but one is that it doesn't involve the use of your own qi.
As a practitioner you need a personal practice as well, preferably Tai Chi if you are going to be working with qigong. This to build your overall health and to increase your ability to circulate your energy and that of others. If you don't have a daily practice, now is the time. If there are no Tai Chi instructors in your area, you could start by learning one of our qi gong routines which are good as a daily practice. I would recommend the Da Peng Gong form which is easy to learn from our book.