Very tricky question, but you might be able to do it by adding the following to your Appearance → Custom Design → CSS page:
.feature-title a {
visibility: hidden;
min-width: 800px;
}
.feature-title a[title]:before {
background: black;
background: rgba(0, 0, 0, 0.5);
color: white;
display: inline-block;
font-size: 24px;
line-height: 1;
margin: 0 0 0 -2px;
max-width: 50%;
padding: 24px 48px 18px;
position: absolute;
bottom: 0px;
left: 2px;
text-decoration: none;
}
#featured-post-1 .feature-title a:before {
visibility: visible;
content: "New Title for Bare Feet Centered";
}
#featured-post-2 .feature-title a:before {
visibility: visible;
content: "New Title for Hand Kiss";
}
#featured-post-3 .feature-title a:before {
visibility: visible;
content: "New Title for Demo";
}
#featured-post-4 .feature-title a:before {
visibility: visible;
content: "New Title for Pricing";
}
#featured-post-5 .feature-title a:before {
visibility: visible;
content: "New Title for Lil' Girl Holding Hand";
}
#featured-post-6 .feature-title a:before {
visibility: visible;
content: "New Title for First Bright Blue";
}
Adjust the "content" value for each feature post title.