In new FontAwesome 4.0.0 there is css styles for stacked items.
<span class="fa-stack">
  <i class="fa fa-square-o fa-stack-2x"></i>
  <i class="fa fa-twitter fa-stack-1x"></i>
</span>
.fa-stack {
  position: relative;
  display: inline-block;
  width: 2em;
  height: 2em;
  line-height: 2em;
  vertical-align: middle;
}
.fa-stack-1x,
.fa-stack-2x {
  position: absolute;
  width: 100%;
  text-align: center;
 }
.fa-stack-1x {
  line-height: inherit;
}
.fa-stack-2x {
  font-size: 2em;
}
.fa-square-o:before {
  content: "\f096";
}

I want to do it only without using nested span and i, just only with some css-classes
.myclass1 { ... }
.myclass2 { ... }
<span class=".... myclass2" />
What is the simplest method to achieve the same result (using fa content classes ?)
Update: or is something like the following possible ?
 .myclass1:before { content:     '<span class="fa-stack">
  <i class="fa fa-square-o fa-stack-2x"></i>
  <i class="fa fa-twitter fa-stack-1x"></i>
</span>' }
     <span class=".... myclass1" />
 
     
     
    