Go to "UNITS" and change to Arch. Then change the "units to scale inserted objects" to feet or unitless. Whatever you want. Then go to system variable or type "UNITMODE" on command line. Change that to "1". You should be able to now specify lengths on your command line in the following format: (1'-3") or (1'3") - minus the parenthesis.
UNITMODE-Controls the display format for units. By default, the format for displaying measured values differs slightly from the format used for entering them. (You cannot include spaces when entering measured values.)
0 Displays fractional, feet-and-inches, and surveyor's angles in "report" format using spaces as delimiters
1 Displays fractional, feet-and-inches, and surveyor's angles in "input" format without including spaces and, in some cases, substituting dashes for spaces