So I decided to write up a quick test page to demostrate whether it should work or not and it works for me. I'm not sure if this is exactly what you're looking for but feel free to copy this and load it into your sandbox to test it. 

NOTE: I tried this in Chrome and IE9 and both worked perfectly.

This page is loaded by going to the URL: https://YOUR_ORG/apex/ScrollLockTest?scroll_pos=5000 (if your page name is ScrollLockTest)

the param scroll_pos will tell the page where to scroll to when loaded

The controller:

public class ScrollLockTestController{

    public List<TableObject> tableData {get; set;}
    public Integer scrollPos {get; set;}
    public Boolean hasPosParam {get; set;}
    
    public ScrollLockTestController() {
        // Load test data
        String baseStr = 'Dummy Data ';
        this.tableData = new List<TableObject>();
        
        for(Integer i = 0; i < 500; i++) {
            TableObject obj = new TableObject();
            obj.data = baseStr + String.valueOf(i);
        	tableData.add(obj);
        }
        
        this.hasPosParam = false;
        String scrollPosParam = ApexPages.currentPage().getParameters().get('scroll_pos');
        
        if(scrollPosParam != null) {

            this.scrollPos = Integer.valueOf(scrollPosParam);
            this.hasPosParam = true; 
        } else {
        	this.scrollPos = -1;    
        }
    }
    
    public class TableObject {
        public String data {get; set;}
    }
}
           
           
           
           
           
           
           
           

The VF Page: 

<apex:page controller="ScrollLockTestController">
    <apex:pageBlock>
    <apex:pageBlockTable value="{!tableData}" var="obj">
    	<apex:column value="{!obj.data}"/>
    </apex:pageBlockTable>
    </apex:pageBlock>
    <script>
        pagePos = {!scrollPos};
        function savePos() {
        	pagePos = (document.pageYOffset?document.pageYOffset:document.body.scrollTop);
        }
        
        function restorePos() {
			window.scrollTo(0, pagePos);
        }
    </script>
    <apex:pageBlock rendered="{!hasPosParam}">
        <script>restorePos();</script>
    </apex:pageBlock>
</apex:page>

A couple things to note:

1) This page currently just checks for the existence of a page position param. I added the javascript method to save the param when reloading but you can take it from there.

2) I used a page block to render the script tag if the param was present. This is just a sloppy quick way to do it so obviously another way would be used for a production app.

Let me know if you have any questions.