If I understand your req correctly, this may work.
I am assuming cell A2 down is your input & B2 down is your output.
Col C onwards will be intermediate values; I am giving a soln for max 15 lines per cell but I think the limit will be like 125-126 (max cols in excel / 2) only matter of copying the formula across
Steps
1) Set cell C1 & C2 to 0, cell D2 to empty
2) Put these formulae:
E1 = C1 + 1
E2 = IF(C2 < LEN($A2), IF(ISERR(FIND(CHAR(10), $A2, C2+1)), LEN($A2), FIND(CHAR(10), $A2, C2+1)), 99999)
F2 = IF(E2 = 99999, D2, D2 & E$1 & "." & MID($A2, C2+1, E2 - C2)) << Modify this as per your format req
3) Select E1:F2 and drag (copy) right across 1:2 rows. Copy upto AH col. AG1 should be 15 now (the 15 limit I was talking about). If you need more continue the copy
4) Set the formula:
B2 = AH2 (or until you copied, the cell with blank in row 1)
For B2 set Format > Cells > Allignment > check Wrap text
5) Put your text in A2 & verify result in B2:
My test case
A2
TESTtest
test2
test3
test4
B2
1.TESTtest
2.test2
3.test3
4.test4
6) If OK, copy row 2:2 down & keep putting your values in Col A
You can very easily do this with Macro also, it will be cleaner & easier to code.
bchat