Time picker needed.

I’ve looked all over the internet, but I cannot find any decent explanation on how to get a drop down time picker in Gravity Forms. So I’m hoping someone here is willing to help me out.

What I need would be extremely simple in html:

<select name="hours">
<option value="10">10</option>
<option value="11">11</option>
<option value="12">12</option>
<option value="13">13</option>
</select>
:
<select name="minutes">
<option value="00">00</option>
<option value="15">15</option>
<option value="30">30</option>
<option value="45">45</option>
</select>

So, basically what I need is a drop down for the hours (24H format) ranging from 10 to 23 and a drop down for the minutes with an interval of 15.

Please help!