Use the below Code on CRM form Load Event to Create a Custom Button on the 
   CRMform:

  /* Code  to Create a Button on CRM FORM */

/* Convert TextBox to Button */
function create_button_from_textattribute(fieldname, buttontext, buttonwidth, clickevent) {
    functiontocall = clickevent;
    crmForm.all[fieldname].DataValue = buttontext;
    crmForm.all[fieldname].style.borderRight = "#3366cc 1px solid";
    crmForm.all[fieldname].style.paddingRight = "5px";
    crmForm.all[fieldname].style.borderTop = "#3366cc 1px solid";
    crmForm.all[fieldname].style.paddingLeft = "5px";
    crmForm.all[fieldname].style.fontSize = "11px";
    crmForm.all[fieldname].style.backgroundImage = "url(/_imgs/btn_rest.gif)";
    crmForm.all[fieldname].style.borderLeft = "#3366cc 1px solid";
    crmForm.all[fieldname].style.width = buttonwidth;
    crmForm.all[fieldname].style.cursor = "pointer";
    crmForm.all[fieldname].style.lineHeight = "14px";
    crmForm.all[fieldname].style.borderBottom = "#3366cc 1px solid";
    crmForm.all[fieldname].style.backgroundRepeat = "repeat-x";
    crmForm.all[fieldname].style.fontFamily = "Tahoma";
    crmForm.all[fieldname].style.height = "20px";
    crmForm.all[fieldname].style.backgroundColor = "#cee7ff";
    crmForm.all[fieldname].style.textAlign = "center";
    crmForm.all[fieldname].style.overflow = "hidden";
    crmForm.all[fieldname].attachEvent("onmousedown", push_button);
    crmForm.all[fieldname].attachEvent("onmouseup", release_button);
    crmForm.all[fieldname].attachEvent("onclick", functiontocall);
    crmForm.all[fieldname + '_c'].style.visibility = 'hidden';
}

function push_button() {
    window.event.srcElement.style.borderWidth = "2px";
    window.event.srcElement.style.borderStyle = "groove ridge ridge groove";
    window.event.srcElement.style.borderColor = "#3366cc #4080f0 #4080f0 #3366cc";
}
function release_button() {
    window.event.srcElement.style.border = "1px solid #3366cc";
}

/* tell the button what to do */
function Savetheform() {
    /* the function */
    document.getElementById('frame_ViewComp').src = "/isv/PostalCodeAddress/HTMLPage.htm";
    document.getElementById('divCompanyInfo').style.display = 'block';
}
create_button_from_textattribute('aa_addressbutton', 'Get Address', '100px', Savetheform);