Dont give up man , you learn , the trick is to dont afraid if the end of world comming , ok you make wrong buy another seal and thats all , so simple.
For the tools that you ask , sure you can do the job with simple tools or with other methods, the diference is that the oem tools do the job faster , and in most cases more corectly, a example is that with a seal puller can pull out the seal without damage it , so you can use again the same seal , with a pressure sleeve can put the seal without to take measurements of the deep , just tap until the tool touch the case, but even and with theese specialty tools must do some practice until you learn how to use it correctly, and must know that many of theese tools maybe look very futuristic, but in praxis are not so friendly.