The plugin comes with two sets of default icons (16px and 32 px).  It also includes extra icons that match those for your use.

Don’t like those icons?

You could do one or more of the following:

1. Switch images off
2. Use Css to replace the text with your own images
3. Write own formatting routines

Switch images off

You could choose just to have the link text for the actions behind the icons.  See the “Listing events’ settings.

Use Css to replace the text with your own images

First switch the default  images off and then use css to show your chosen icons instead.

There are various techniques that one can use to replace text with an image. The following was used to demonstrate the above replacement using the plugins html classes.

a.icalsubscribe { 
    display: block;
    height: 50px;
    width: 50px;
    background-image: url(http://i.stack.imgur.com/XtpTm.png);
    background-size: 50px 50px;
    text-indent: -9999px;
    overflow: hidden;
}

Some of the link classes that you may wish to define image icons for are:

• subscribe
• icalsubscribe
• addtogoogle
• hrefaddtogoogle
• hrefmap
• timezone
• refresh

Add the extra css :

1. Either to your custom themes stylesheet (not to one that gets updated automatically, because you will lose your modifications), or
2. use something like jetpacks wordpress custom css, or
3. use a custom ical events list css

Write own formatting routines

See the pluggable files in each plugin folder.  Use the function there as a base for your new function.  Add your function to your custom themes function.php or to your own site specific snippets plugin.

some pluggable functions in amr-icalevents-list

• add_cal_to_google
• add_event_to_google
• amr_ical_showmap
• amr_show_refresh_option
• amr_format_tz

some pluggable functions in amr-events

• amr_subscribe_to_event_series
• amr_subscribe_to_event