I found the answer that I think may help other people trying to accomplish this as well. The code below shows how to make a Custom Basemap Gallery using your own Basemaps (not ArcGIS maps). In this case, it will create two basemaps for a single gallery.
<script>
dojo.require("esri.map");
dojo.require("dijit.form.Button");
dojo.require("dijit.layout.BorderContainer");
dojo.require("dijit.layout.ContentPane");
dojo.require("esri.dijit.BasemapGallery");
dojo.require("esri.arcgis.utils");
var map;
function init() {
map = new esri.Map("map");
createBasemapGallery();
}
function createBasemapGallery() {
//manually create basemaps to add to basemap gallery
var basemaps = [];
var firstBasemapLayer = new esri.dijit.BasemapLayer({
url:"--url to your basemap--"
});
var firstBasemap = new esri.dijit.Basemap({
layers:[firstBasemapLayer],
title:"First Basemap",
thumbnailUrl:"images/firstbasemap.png"
});
basemaps.push(firstBasemap);
var secondBasemapLayer = new esri.dijit.BasemapLayer({
url:"--url to your basemap--"
});
var secondBasemap = new esri.dijit.Basemap({
layers:[secondBasemapLayer],
title:"Second Basemap",
thumbnailUrl:"images/secondBasemap.png"
});
basemaps.push(secondBasemap);
var basemapGallery = new esri.dijit.BasemapGallery({
showArcGISBasemaps:false,
basemaps:basemaps,
map:map
}, "basemapGallery");
basemapGallery.startup();
dojo.connect(basemapGallery, "onError", function (error) {
console.log(error);
});
}
dojo.ready(init);
Once this is used in your HTML file, you can then add code to add it to your webpage.
<div data-dojo-type="dijit.layout.BorderContainer"
data-dojo-props="design:'headline', gutters:true"
style="width:100%;height:100%;">
<div id="map"
data-dojo-type="dijit.layout.ContentPane"
data-dojo-props="region:'center'"></div>
<div data-dojo-type="dijit.layout.ContentPane"
data-dojo-props="region:'right'" id="rightPane">
<div data-dojo-type="dijit.layout.BorderContainer"
data-dojo-props="design:'headline', gutters:false"
style="width:100%;height:100%;">
<div id="paneHeader"
data-dojo-type="dijit.layout.ContentPane"
data-dojo-props="region:'top'">
<span>Select Basemap</span>
</div>
<div data-dojo-type="dijit.layout.ContentPane"
data-dojo-props="region:'center'">
<div id="basemapGallery"></div>
</div>
</div>
</div>
</div>
A tutorial for this can be found here.