ALV report: How to merge 2 columns into 1 column?

Hello,

I have a list of data which I would like format the header to look as below:

-

---

| -

---

Quater 1---- | -

---

Quater 2 -

---

| -

---

Quater 3---- | -

---

Quater 4---- | <--- header 1

-

---

| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | <--- header 2

-

---

| -

---

F---- | -

---

S - | -

---

F-- | -

---

S - | -

---

F-- | -

---

S - | -

---

F-- | -

---

S - | < - header 3

-

---

xxxxxxx | xxxxxx | xxxxx | xxxxx | xxxxxx | xxxxx | xxxxxx | xxxxx | <--- data lines start here....

Is there anyway I able to achieve this layout?

I found quite a numerous of "cell_merge" information on ALV but I do not know how exactly it work and how to modify it?

Would be appreaciate if anyone of you able to guide me with sample code.

Thanks in advance,

Aish :P