Is this close enough:
0010 BEGIN ; PRINT 'MODE'($000F$),'CS',
0020 PRINT 'OPTION'("GridMLVersion","0"),
0030 LET G=10; GRID G,@(38,1,40,8)
0040 LET G'COLUMNSWIDE=4,G'ROWSHIGH=5,G'ENTERMODE=2
0050 LET G'COLUMN=0,G'ROW=0,G'COLUMNWIDTH=8,G'CELLTYPE$="Multi_line"
0060 FOR R=1 TO 5; FOR C=1 TO 4; LET G'COLUMN=C,G'ROW=R
0070 LET G'VALUE$="C"+STR(C)+"/R"+STR(R); IF R/C=1 THEN LET G'LOCK=1
0080 NEXT ; NEXT ; LET G'CURRENTCOLUMN=2,G'ROW=1; SET_FOCUS G
0090 WAIT:OBTAIN *; IF CTL=4 THEN STOP
0100 GOTO WAIT
<enter> stops editing the cell, and the next <enter> moves focus to the next cell.