You can add heat shielding to any part by editing the part's .cfg file. These are located in GameData/<plugin>/Parts/ ('squad` is the directory name for default parts)

A part config looks something like this:

PART
{
    // stuff
    MODULE
    {
          // stuff
    }
    MODULE
    {
          // stuff
    }
    RESOURCE
    {
          // stuff
    }
    RESOURCE
    {
          // stuff
    }

}

To add some capability offered by a mod, you usually add some new MODULE sections and possibly RESOURCE sections.

Checking one of DRE's heatshield configs, here are the sections that add shielding:

MODULE
{
    name = ModuleHeatShield
    direction = 0, -1, 0 // bottom of pod
    reflective = 0.05 // 5% of heat is ignored at correct angle
    ablative = AblativeShielding
    conductivity = 0.01
    loss
    { // loss is based on the shockwave temperature (also based on density)
        key = 650 0 0 0 // start ablating at 650 degrees C
        key = 1000 64 0 0 // peak ablation at 1000 degrees C
        key = 3000 80 0 0 // max ablation at 3000 degrees C
    }
    dissipation
    { // dissipation is based on the part's current temperature
            key = 300 0 0 0 // begin ablating at 300 degrees C
            key = 500 180 0 0 // maximum dissipation at 500 degrees C
    }
}
RESOURCE
{
    name = AblativeShielding
    amount = 250
    maxAmount = 250
}

Add those two sections to your part and tweak the setting to get it right. In addition, you will want to increase the part's maxTemp.

I haven't played around with adding shielding, so I can't help with the parameters, but the DRE thread should already have plenty of information. Google the thread for a particular parameter with the search query like

direction site:http://forum.kerbalspaceprogram.com/threads/54954-0-90-Deadly-Reentry-v6-5-3-Beta-Mar-6-2015