Hey, so here's what I've done so far:

1. Got MagicLauncher, works fine!
2. Tried to get Modloader, but since I have an old mac, I cannot update Java for Modloader to work. Unless someone has a workaround for this (haven't found any), I can't get this mod.
   
3. Tried to add Optifine sans Modloader, got a "no mods found!" error.
   

4. Found this, tried that, and now Optifine works! However, I cannot connect to the server with the login, so I can only use Optifine offline. The error code when I then select "Details" is below.

   MagicLauncher 0.9.8  
   java.home: /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home  
   java.runtime.name: Java(TM) 2 Runtime Environment, Standard Edition  
   java.runtime.version: 1.5.0_30-b03-389-9M3425  
   os.name: Mac OS X  
   os.version: 10.5.8
   os.arch: i386
   sun.arch.data.model: 32
   javax.net.ssl.SSLException: java.lang.RuntimeException: Unexpected error: java.security.InvalidAlgorithmParameterException: the trustAnchors parameter must be non-empty
   at com.sun.net.ssl.internal.ssl.Alerts.getSSLException(Alerts.java:189)
   at com.sun.net.ssl.internal.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1642)
   at com.sun.net.ssl.internal.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1605)
   at com.sun.net.ssl.internal.ssl.SSLSocketImpl.handleException(SSLSocketImpl.java:1588)
   at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1165)
   at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1142)
   at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:450)
   at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:166)
   at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:133)
   at magic.launcher.aj.a(Unknown Source)
   at magic.launcher.z.run(Unknown Source)
   at java.lang.Thread.run(Thread.java:655)
   Caused by: java.lang.RuntimeException: Unexpected error: java.security.InvalidAlgorithmParameterException: the trustAnchors parameter must be non-empty
   at sun.security.validator.PKIXValidator.< init>(PKIXValidator.java:56)
   at sun.security.validator.Validator.getInstance(Validator.java:146)
   at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.getValidator(X509TrustManagerImpl.java:105)
   at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:167)
   at com.sun.net.ssl.internal.ssl.JsseX509TrustManager.checkServerTrusted(SSLContextImpl.java:320)
   at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1020)
   at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:120)
   at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Handshaker.java:574)
   at com.sun.net.ssl.internal.ssl.Handshaker.process_record(Handshaker.java:510)
   at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:888)
   at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1131)
   at com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1158)
   ... 7 more
   Caused by: java.security.InvalidAlgorithmParameterException: the trustAnchors parameter must be non-empty
   at java.security.cert.PKIXParameters.setTrustAnchors(PKIXParameters.java:183)
   at java.security.cert.PKIXParameters.< init>(PKIXParameters.java:103)
   at java.security.cert.PKIXBuilderParameters.< init>(PKIXBuilderParameters.java:87)
   at sun.security.validator.PKIXValidator.< init>(PKIXValidator.java:54)
   ... 18 more  
   

Just to let you know, every time you see "init" with the brackets, there was originally no space between the < and init. I had to add the space or the code would not show.

If anyone can help, please do so!