You don't. SAW can only be done in 1G rolled on pipe, commonly used on spiral pipe production, i.e. coil of steel rolled into a specific diameter with one SAW head at the bottom of the as rolled to weld the inside then as rolled one SAW head at the top seconds later. It's slick to watch.
Also note the 6G test can be done with a backing, (Figure 4.24 - SMAW, FCAW are best) It will limit you to backing or backgouging but gets you everything in one test with backing/backgouging, but CJP - TYK joints. (WPS Table 4.1 & Weldor Qual Table 4.10) In this way you use 1 process and can be written as Pre-Qualified. (except for GTAW or GMAW noting GMAWs (short circuit) is not pre qualified and GMAWsp (spray) is usually kept in the flat, horizontal positions.) See 3.2.1 and Table 4.10 - 4.11 and note Figure 4.24 which calls for a 60 degree groove with or without backing any position. Even a WPS by qualification allows Section 3 prequalified groove details, Table 4.5 #31
Hope this helps