Copy the string "5A1N;B2;K5;I10.0.0.255;J443;Z10.0.0.255" into an ascii-> hex conversion tool (there are free websites many available online). Then use the resulting hex as an input to the option 43 field in windows. There is a "details" window where it shows you both the hex and ascii for the value you input. If the ascii there looks like the original string, then you probably have it right.
If there is a way to input ascii directly, it would be great if someone else can chime in to educate us. (or if Microsoft can add one to save us the hassle of converting to hex in the future). None of the documentation I found suggest that direct ascii method exists yet.