you can give this one a try, its using looping to scroll, it repeats the action every 500 milliseconds, if it works to fast or to slow just adjust the delay time
<?xml version="1.0" encoding="utf-16"?>
<!--VoxCommando 2.1.4.5-->
<commandGroup open="True" name="Roku Scrolling " enabled="True" prefix="" priority="0" requiredProcess="" description="">
<command id="808" name="Scroll direction (experimental) 2.0" enabled="true" alwaysOn="False" confirm="False" requiredConfidence="0" loop="True" loopDelay="500" loopMax="50" description="">
<action>
<cmdType>Scrape.Post</cmdType>
<params>
<param>http://YOUR_ROKU_IPADDRESS:8060/keypress/{1}</param>
<param />
<param />
<param />
<param>text/html</param>
</params>
<cmdRepeat>1</cmdRepeat>
</action>
<phrase>Roku Scroll</phrase>
<payloadList>Left, Right, Up, Down</payloadList>
</command>
<command id="890" name="Stop Scrolling (experimental) 2.0" enabled="true" alwaysOn="False" confirm="False" requiredConfidence="0" loop="False" loopDelay="0" loopMax="0" description="">
<action>
<cmdType>VC.StopMacro</cmdType>
<params />
<cmdRepeat>1</cmdRepeat>
</action>
<phrase>Roku Stop Scrolling </phrase>
</command>
</commandGroup>