Not a big deal to loop the lines together as long as it is only run a couple of minutes at a time.
Brass caps are the way to go to stop from losing all the fluid, however, I normally just let them hang in a bucket and top off the trans when I am done. Figure it cannot hurt to have cleaner fluid in, especially since trans oil intervals are so long.
If you go to pinch the lines with vise grips or line clamps and the lines seem stiff REPLACE them! When they are stiff, they are flaking on the inside and that means contaminents in the system which can clog filters and passages. Rubber contamination is one of the most consistent causes of hydraulic systems failures on vehicles.
Also, use a trans cooler/air conditioner cleaner solution which you can get at most parts houses. You will be shocked when you see what come out of there (most people have never done this... so don't feel too bad!). If you have a separate cooler from your radiator, use one can for each cooler... yeah that costs more, but come on... your coolers haven't been cleaned once in 25 years!
Finally, put a Trans filter in line. There are many good ones out there... make sure it is magnetized. My favorite one is admittedly made by the company I work for, Cardone Industries, but that does not reduce the cool factor! It is a billet aluminum Power Steering filter that can also be used as a trans filter... called "Magna Pure" (Part # 20-0038F). May have to be special ordered as they are new. It is for 3/8 lines only, though we sell a more normal magnetized filter for smaller lines.
What's great is you can install inline and, if an issue arises or just to see the health of your system, you can disassemble it by popping out one snap ring. Examine the contents of both the magnet and the filter element. Great for trans and PS. No, I cannot sell these directly as my accounts would not like that much!
BTW, you can learn more at cardone.com and watch a free 3 minute video about how to properly flush you PS system as well as see the filter. There is also a lot of good tech info available there, all free of charge.
Hope that did not get too far off topic!